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Most people outside of a laboratory haven’t come across Nα-Benzoyl-DL-arginine 4-nitroanilide hydrochloride, known among researchers as BAPNA. Its story starts in the heart of twentieth-century biochemical research, in a world hungry for sharper lab tools to study enzymes. Scientists searched for easy, reliable substrates to probe protease activity—especially trypsin. BAPNA stepped into that role, springing from the era when enzyme kinetics leaped forward thanks to synthetic chemistry. Its first broad use happened decades ago, as biochemists harnessed it for digestion studies, hoping to better chart how proteins break down and how this process underpins broader health issues. Over time, BAPNA hasn’t faded into obscurity. Instead, it’s become a staple reagent you’ll find in research on everything from digestive disorders to research into protease-inhibiting drugs. Scientists who work with proteolytic enzymes lean on its reliability and clear readout, and from my own bright-eyed days as a lab assistant, the yellow color change—when BAPNA meets trypsin—still stands out as one of the more satisfying sights during those long runs at the bench.
BAPNA is a synthetic molecule, used not in medicine cabinets but as a tool for probing enzyme function. Its core value sits in assays, those low-key yet crucial experiments that labs use to measure whether an enzyme like trypsin is doing its job. If the enzyme is present and active, it cleaves BAPNA, turning a colorless solution vivid yellow. That visible change means no fancy machines for a basic result, making life easier for underfunded research teams or high school science initiatives trying to stretch a dollar. I’ve seen students get genuinely excited about science when this substrate produced its dramatic color shift, offering a clear bridge between the invisible molecular world and the hands-on reality of chemistry.
BAPNA looks like a white to yellowish crystalline powder. Chemically, it’s stable under standard conditions—enough to make shipping, storage, and day-to-day work relatively frictionless. The hydrochloride salt form gives good solubility in water, which matters in enzyme assays where everything needs to dissolve cleanly. 4-nitroaniline, one fragment released by the reaction, has a strong absorbance at 405 nm wavelenght. This simple feature lets even entry-level spectrophotometers pick up its presence. Physically, BAPNA’s low toxicity means it fits comfortably inside academic teaching kits as well as higher-end industrial research setups. In a world where many lab reagents carry hefty health warnings, this is no minor perk.
Accuracy in chemistry rests on clear labeling and reliable product specs. BAPNA often comes with its purity levels marked—typically over 98 percent—alongside batch numbers and storage guidance. High-purity BAPNA matters if you want dependable and reproducible results. Labels usually spell out the correct chemical name, synonyms, hazard symbols, as well as pointers for safe handling. From my own experience in chemical stockrooms, clear labeling means fewer mistakes, especially for young lab techs juggling dozens of similar-looking bottles. If anything in research deserves this level of attention, it’s the basic building blocks like BAPNA that underpin hundreds of studies worldwide.
Synthesizing BAPNA involves coupling benzoyl-arginine with 4-nitroaniline through established peptide bond-forming techniques. The arginine is first protected to keep chemoselectivity, while the nitroaniline provides the color-producing punch. Hydrochloride addition steps in to stabilize the product and boost solubility. While labs with organic synth expertise might make their own, most rely on specialized chemical suppliers who can guarantee purity and consistency. Scale matters here; even a small impurity can throw data off, wasting weeks of work. I remember a frustrated postdoc who fought questionable results for months, only to finally pin problems down to an off-brand substrate—little details like synthesis quality can define a whole project’s outcome.
The defining feature of BAPNA is its susceptibility to trypsin cleavage at the arginine bond. Addition of trypsin, chymotrypsin, or certain other serine proteases cuts it neatly, freeing 4-nitroaniline. The simplicity of the reaction design invites chemists to tinker: researchers often modify the benzoyl group or swap out the nitroaniline to tailor substrates for broader or narrower enzyme specificity. These analogs feed innovation, expanding assay possibilities into new enzyme families or disease models. I’ve seen creative teams engineer substrates that light up under UV, or only release signal in particular cell types. At its core, BAPNA serves as a springboard, showing how a well-built molecule can power decades of new thinking.
Seasoned researchers know BAPNA by many aliases: Nα-Benzoyl-DL-arginine p-nitroanilide hydrochloride, BA-pNA, or sometimes the less wieldy full IUPAC name. Product catalogues list it under diverse abbreviations. These alternatives cause headaches when ordering or sharing protocols—one slip, and a lab can wind up with the wrong isomer, substrate, or grade. In practice, the confusion over name variations is more than a minor nuisance. I keep a printout of common synonyms taped inside my notebook, and I recommend others do the same. This minor step dodges hours of research delays and cross-lab miscommunication.
BAPNA ranks on the safer side among lab reagents but still benefits from thoughtful handling. Dust can irritate the respiratory tract, and direct skin or eye exposure never helps anyone. Labs using BAPNA need good airflow and basic PPE—chemistry’s version of wearing seatbelts. National safety standards urge users to store BAPNA in sealed, labeled containers kept cool and dry. Waste disposal follows local chemical rules, since the breakdown products—nitroanilines—carry their own environmental baggage. Training lab personnel on these points keeps both people and the planet better off in the long run. Watching new students, I often see safety corners cut during routine assays, but reinforcing basic operational discipline ensures years of smooth research without unnecessary mishaps or accidental exposures.
Protease assays make up the bulk of BAPNA’s workload, especially in diagnostics and drug discovery. Hospitals and clinics value precise enzyme activity readings to diagnose pancreatic insufficiency or track recovery from gut injuries. Pharmaceutical companies use BAPNA-based screens to scout for new protease inhibitors, tapping into growing demand for antiviral drugs, clotting therapies, or even cancer treatments. Academic labs fit BAPNA into a wider range of test-tube detective work, including plant biochemistry, aging research, and basic enzyme structure studies. During my own early research days, I saw BAPNA holding court at nearly every major biochemistry bench—a workhorse for basic and applied science alike. Its versatility and clarity lower the entry bar for quality science, something few chemicals can claim.
BAPNA continues to fuel innovation in lab methods. Advances aim to miniaturize assays, automate measurements, or adapt the substrate for multiplexed readouts like high-throughput screening. Recent work has leveraged BAPNA analogs in microfluidic chips, accelerating the pace of data collection for new enzyme-targeted drugs. The colorimetric punch remains unchanged, but researchers push to make the process faster, cheaper, and more reproducible. Collaborations between chemists and engineers keep delivering tweaks—improved buffers, hybrid substrates, more sensitive detectors—all aiming to make enzyme activity tracking nearly routine. My interactions with early-stage startups make it plain: even in an age of CRISPR and AI, classic substrates like BAPNA underpin the lab’s daily work. Making these processes more robust changes practical research outcomes for diseases that need smarter therapies, and that carries real weight.
Toxicity profiles for BAPNA remain relatively mild, but research doesn’t stop at assumptions. Animal studies track breakdown products, making sure no subtle harm creeps up with chronic handling. Regulatory agencies watch for skin or eye irritation, inhalation risk, and environmental persistence—especially for nitroanilines produced after enzymatic cleavage. Safety testing takes center stage in educational settings where non-expert users handle chemistry in less controlled setups. Keeping updated on new toxicity findings isn’t just bureaucracy; it lets institutions adapt protocols before small annoyances become bigger health issues. From my own teaching experience, young scientists benefit from knowing the real risks and shaping habits that last a lifetime.
The chemistry toolkits of tomorrow won’t push BAPNA aside anytime soon. It earns its keep in laboratories around the world—its straightforward, reliable signal makes it hard to beat, especially for teaching and entry-level enzyme investigations. That said, there’s room for improvement and innovation. Researchers continue looking for derivatives with sharper specificity or more environmentally benign breakdown products. Labs hope to pair BAPNA-inspired molecules with next-generation readouts like fluorescence, electrochemistry, or portable sensors. Advances in data sharing should help uncover fresh applications for BAPNA analogs, particularly in point-of-care diagnostics or rapid on-site food safety testing. Looking ahead, BAPNA and its evolutionary cousins have a real shot at helping scientists respond faster to new health threats, environmental changes, or biomanufacturing needs. Their utility depends on ongoing research and smart regulation, and on the foundational efforts of scientists who have kept these classic reagents in play.
Some chemicals show up on a lab bench so often, they blend into the background. Nα-Benzoyl-DL-arginine 4-nitroanilide hydrochloride—or BAPNA, for short—has scooped that honor in many biochemistry labs. At a glance, this long name looks intimidating. People working in labs, myself included, remember it as the yellow powder that says something about enzymes most textbooks forget to make interesting. Yet BAPNA makes enzyme activity visible, almost like switching on a traffic light for proteins.
In practical terms, BAPNA behaves less like a chemical and more like a test kit. It gets used to detect how active trypsin and other serine proteases are. These are enzymes, often found in the digestive tracts of animals, that cut proteins apart. BAPNA lets biochemists measure this activity by producing a yellow color if the enzyme does its job. Even undergrad students remember the “yellow color means it worked” rule.
Scientists go through a basic process: Mix enzyme and BAPNA, then watch what happens. If trypsin chews up BAPNA, a product called p-nitroaniline appears and turns the solution yellow. This yellow color isn’t there for fun. It can be measured with a spectrophotometer, turning a vague “how active” question into a number. Numbers matter. They let us compare enzyme activity across many conditions—temperature, pH, disease state, inhibitor presence. Some research groups use BAPNA for studying enzyme malfunction in diseases like pancreatitis, or in the testing of digestive enzyme supplements.
Without BAPNA, some enzyme studies would take weeks instead of hours. I spent part of my training comparing the activity of trypsin from different sources. With BAPNA, I could see small differences right away rather than waiting for slow protein gels or complex digests. Having a direct visual cue changes the pace of research, which can speed up drug testing or diagnosis development. Fast and simple tests get used far beyond basic research—clinical labs count on similar reactions to guide patient care.
BAPNA’s importance also highlights challenges. Quality matters, and low-grade batches with impurities throw off results. Each lab needs good supply chains, detailed documentation, and training for safe handling. Some countries face price markups or supply shortages, which stifles research. Easing access means investing in chemical manufacturing standards, supplier audits, and even local production facilities for basic reagents.
On the health safety front, training can’t stop at protocol sheets. Inhaling the powder or exposing skin may cause irritation, so labs need good ventilation and protective wear, and regular audits help catch safety slip-ups.
Some researchers are developing alternatives to BAPNA that track not just trypsin but a wider range of proteases. Yet, for raw simplicity and reliability, BAPNA keeps delivering value. Open sharing of test data, stricter oversight of reagent quality, and building skills in emerging science hubs will keep this humble yellow-dye reaction relevant. It’s a vivid example of how one compound, paired with rigor and wide access, can help science move forward.
Anyone who's handled protein analysis or dabbled in enzyme kinetics has likely met Nα-Benzoyl-DL-arginine 4-Nitroanilide Hydrochloride. Lab folks toss around abbreviations like BAPNA, but the stuff in the bottle is what counts—and how that bottle rests on the shelf means everything. Chemical safety isn't about ticking boxes. It’s the difference between precise results and a wasted week, sometimes worse.
Keep this compound in a cool, dry place, well away from sunlight—think temperature-controlled cabinets or refrigerators, not the top shelf next to the window. Moisture and sunlight chew up a lot of reagents, but BAPNA shows this wear-and-tear quickly: it's sensitive and will break down if left out, even for a few days in lousy conditions.
Lab techs and grad students will recognize that faded label or clumpy powder as trouble. Fresh BAPNA appears as a crystalline yellow substance. Solid samples soak up water from the air, making purity drop and changing the results for enzyme tests. If left at room temperature with humidity floating around, the workload can double after a single mistake.
Keep things honest about lab routines: people skip steps for convenience. Yet, storing this powder at room temperature, especially near open windows or heating vents, shortens its lifespan. Refrigeration between 2 °C and 8 °C, sealed in a tightly closed container with a desiccant packet, fights off hydrolysis and oxidation.
Some overlook the risk of contamination—loose caps, dirty scoops, gloves that handled coffee mugs before opening a bottle. This carelessness translates into false readings and wasted budget. One compromised batch doesn’t just set you back a day. I've seen grant deadlines slip because a handful of samples went off after a storage fumble.
Label the container with date opened, storage instructions, and your initials. Store it apart from volatile solvents and acids since vapors corrode chemicals or leak into the powder. It's tempting to reuse containers or pile similar bottles together, but clear separation prevents wild-card cross-reactions.
Documenting storage conditions and movements gives traceability—a must for labs running regulated tests or working toward GLP certification. Tidy records leave no wiggle room for confusion once an experiment fails or a quality check points to botched reagents.
Established chemical suppliers and Sigma-Aldrich, Thermo Fisher, and PubChem recommend storage below ambient temperature and desiccation. These guidelines spring from years of stability studies, not internet rumors. Peer-reviewed literature agrees: the powder stays stable for years in a fridge, but at room temperature, stability sinks—especially in humid regions.
If labs don’t have a dedicated fridge, insulated lockboxes with silica gel packets on a cool shelf work for short periods. Regular checks for color changes and clumping spot trouble before it spreads.
Make a checklist for all new staff and interns. Post signs in the chemical storage room explaining which chemicals need refrigeration. Rotate stock by using older supplies first. Share storage stories at lab meetings—everyone has a tale of a project sunk by bad reagents.
It comes down to respect for materials, respect for data, and a little humility. Most chemical failures tie back to a missed storage detail. Treat BAPNA right, and the rest of the workflow will thank you.
A researcher stares down a little glass vial, bright label reading “Nα-Benzoyl-DL-arginine 4-Nitroanilide Hydrochloride.” To most people, that looks like an intimidating tongue-twister. In the lab, precision matters. Ask any scientist about assay headaches—the blame often lands on questionable purity. Here, purity often hovers above 98%. This isn’t just some arbitrary number. Impurities in biochemistry ripple out into botched experiments and wasted days. In enzymology, for example, using a substrate like this requires confidence that what’s scooped from the bottle is exactly what’s listed. If contaminants sneak in, the results veer off course, which leads to incorrect data and serious doubts about enzyme specificity or rate calculations.
Nα-Benzoyl-DL-arginine 4-Nitroanilide Hydrochloride, usually written as BAPNA HCl, often turns up in protease assays, especially in studies of trypsin. Poor purity undermines the accuracy of enzyme kinetics, shifting the focus away from the real science and into troubleshooting messes born from bad reagents. A bottle labeled "95% pure" won't cut it for precision work. Reputable suppliers push the number to 98% or even 99% for research-grade BAPNA HCl. Nothing halts a productive week faster than repeating an assay because the substrate came with a mystery sidekick.
Down the hall, lab mates argue about “how much to weigh out.” That figure comes from the chemical’s molecular weight. For BAPNA HCl, it clocks in at about 406.82 g/mol—adding the hydrochloride clutch to the original base compound. Getting that right means making accurate stock solutions. Misjudge here, and the experiment is already off balance. Imagine a protein quantification: use the wrong molecular weight, and measurements drift, concentrations skew, and downstream analyses carry tiny errors that snowball.
Take enzyme specificity assays. Calculating exact substrate concentrations gets tricky if you’re unsure about the correct molecular mass. Laboratories depend on that number for everything from molarity calculations to calculating turnover rates. In published work, reviewers double-check that mass, because it anchors reliable experimental results. Once, a colleague thought they’d found a novel inhibitor—until retracing steps led straight to a math error related to the wrong molecular weight on the reagent label. Hours lost, data tossed.
Trust in the science grows from these building blocks. Many clinical investigations and diagnostics involve enzyme activity screens, where BAPNA HCl works behind the scenes. Good practice relies on checking the supplier’s certificate of analysis before even cracking the lid. It’s not obsessive; it’s practical. A small oversight with purity or molecular weight undoes entire projects, wastes grant funds, and delays advances in understanding diseases and treatments.
Addressing these issues means scientists need reliable sourcing. Always crosscheck chemical details and lot certificates with published literature. Workplaces should encourage running small verification tests when new batches arrive, even from previously trusted suppliers. Over time, a culture of careful verification saves enormous effort. As grant timelines tighten and peer review demands accuracy, the basics—purity and molecular weight—hold steady as foundation stones for research. Every reliable assay starts with these boring but absolutely crucial facts.
Lab work always brings out the basics: “Will this dissolve?” Nα-Benzoyl-DL-arginine 4-Nitroanilide Hydrochloride—often just called BAPNA—is one of those compounds that makes you check twice before pouring it into a bottle. Every enzyme kinetics kit uses some version of this substrate, and nobody wants flecks of undissolved powder mess up their absorbance readings.
In my years hunting for reliable spectrophotometer readings, BAPNA has earned a reputation. Plenty of resources and lab notes say it “dissolves in water,” yet the reality turns out less straightforward. BAPNA, being a hydrochloride salt, does dissolve, but not effortlessly and not at high concentrations. You’ll get by with a warm water bath, maybe gentle swirling or a few minutes with a vortex mixer. At room temperature, it takes patience. Add too much powder or rush the process and you deal with cloudy mixtures and questionable chemistry.
According to Sigma-Aldrich and other reputable suppliers, BAPNA Hydrochloride has moderate water solubility: about 20 mg/mL. Compare that to common table salt, which soaks in at over 350 mg/mL, and you see how unruly BAPNA can be in the hands of an inexperienced technician. Most protocols recommend 1-10 mM working concentrations, which fall well below the solubility limit and play nice with the substrate’s stability.
People in protein labs often turn to polar organic solvents like DMSO or methanol when water stalls the show. Both dissolve BAPNA quite a bit better than room temperature water. DMSO, with a reputation for solvating troublemakers on the bench, quickly makes BAPNA manageable at higher concentrations. Ethanol comes up now and then, but few protocols stick with it unless low water tolerance or unusual downstream requirements exist.
The catch: organic solvents can interfere with your enzyme or protein of interest. Some enzymes react poorly—activity drops or side reactions start popping up. One memorable experiment in my early research years taught me this lesson the hard way. We tried using a DMSO stock for quick dispensing, yet after a few runs noticed a steady drop in trypsin’s punch. It took digging into old literature and talking to a senior postdoc to realize trace DMSO at 2% v/v was the culprit. Switching back to gentle heating and water-only stock solved it overnight.
The secret to getting the most from BAPNA is matching your solution prep with your assay’s demands. Water is the safest bet, with a little warmth and patience helping things along. If clarity escapes you, a brief sonication can smooth out stubborn bits, but overdoing it risks decomposition.
If chasing higher concentrations or fast dissolving, DMSO will save time, though double-check the downstream system won’t mind its presence. Every lab benefits from up-to-date protocol sheets and a few trial runs before running large sample sets—good records and a few pilot experiments save hours wiping buckets clean and recalibrating.
Simple mistakes with solubility waste time and reagents, something no researcher likes to admit when budgets keep shrinking. Rooms full of half-used vials remind me to treat these questions seriously. Little tweaks—like preheating, titrating powders more slowly, or double-checking compatibility—roll into smoother assays with clear results.
For anyone new to biochemical substrates like BAPNA Hydrochloride, ask a senior tech or check not just product specs but shared lab notes. Honest answers about solubility help avoid wasted hours and failed enzyme runs. Consistency in how stocks are handled pays off quickly, with fewer headaches and less second-guessing every cloudy solution.
Experiments using Nα-Benzoyl-DL-arginine 4-Nitroanilide Hydrochloride (commonly called BAPNA) often stir up heated lab debates. People want quick answers—how much substrate should I use? Skip wishful guessing and dig into research: most peer-reviewed protocols suggest a final BAPNA concentration between 0.5 mM and 1 mM. Published enzymology papers, especially those evaluating trypsin activity, frequently hit that sweet spot. This range lets the enzyme's activity show clearly—enough substrate for reliable color change without clogging the reaction with too much or too little reagent.
A lower concentration than 0.5 mM can barely tickle enzyme activity, making the results hard to notice. Too little substrate means the color change from yellow p-nitroaniline just doesn’t leap out during spectrophotometry. Higher than 1 mM, and the background signal gets distracting, plus you burn through reagents faster than needed. Stray too far off, and you either miss weak enzymatic activity or swamp the assay with noise, burning time—and budgets—without payoff.
Through years working both in teaching labs and clinical settings, I’ve watched overambitious newbies think more is always better. It’s not. Excess BAPNA muddies analysis and wastes cash. Even skilled techs run into trouble if they don’t baseline each new batch of reagent with proper controls. A solid test run at 0.8 mM in 50 mM Tris buffer (pH 8.0) often reveals clean, sharp results, enough for undergraduates, research scientists, and diagnostics alike.
Labs without access to high-end plate readers worry about sensitivity; choosing the recommended concentration range makes the color development readable using standard 405 nm spectrophotometers. I remember running samples by eye to check for yellowing, then confirming numbers instrumentally—never trusting just looks when results matter for publication.
The measured absorbance at 405 nm does more than tell you enzyme presence—it reflects whether your protocol respects the reaction’s genuine limits. Assays thrive when you control pH, temperature, and timing just as tightly as BAPNA concentration. Old or improperly stored BAPNA can underperform no matter the measured amount, something the biggest reference books—Berg, Lehninger, Stryer—underline. Turning a blind eye to storage rules sinks assay reliability.
Struggling with inconsistent results? Try prepping fresh BAPNA before each run. Don’t count on miracle stabilization past a week even at four degrees Celsius. Run standards alongside experimental samples, especially after switching suppliers, since purity and batch differences show up right away at these small scales. For tricky enzymes or low activity samples, up the BAPNA close to 1 mM and pair with extended incubation, documenting every tweak. Keep buffer composition constant, since tripeptide interactions mess with some metal-based buffers more than organic ones.
Lean into protocols from big-name journals or national guideline bodies. These groups have battle-tested ranges for BAPNA, plus troubleshooting tips stamped by expert peer review. Trust built through hundreds of results means more than vendor claims. Consistency in these basic details leads to assay runs that people respect, whether developing new diagnostics or teaching kinetic principles. In enzyme assays, clear, repeatable results from a sensible BAPNA starting point beat wild improvisation every time.
| Names | |
| Preferred IUPAC name | N-benzoyl-L-arginine 4-nitroanilide hydrochloride |
| Other names |
BAPNA Benzoyl-Arginine p-Nitroanilide Hydrochloride Nα-Benzoyl-DL-arginine p-nitroanilide hydrochloride Benzoyl-DL-arginine 4-nitroanilide hydrochloride |
| Pronunciation | /ɛn-æl-bɛnˈzɔɪl-diː-ɛl-ɑːˈdʒɪniːn fɔːr-ˌnaɪtrəʊˈænɪlaɪd haɪˌdrɒxɪˈklɔːraɪd/ |
| Identifiers | |
| CAS Number | 90244-62-3 |
| Beilstein Reference | 3544622 |
| ChEBI | CHEBI:71397 |
| ChEMBL | CHEMBL2111692 |
| ChemSpider | 14417 |
| DrugBank | DB03759 |
| ECHA InfoCard | 03a7d872-bb80-4fd7-9f8f-2e5f6c2f2762 |
| EC Number | 3.4.21.4 |
| Gmelin Reference | 84987 |
| KEGG | C02932 |
| MeSH | D015841 |
| PubChem CID | 25165894 |
| RTECS number | CY8579000 |
| UNII | NLB2J96SZV |
| UN number | Not regulated |
| Properties | |
| Chemical formula | C18H22N6O4·HCl |
| Molar mass | 394.85 g/mol |
| Appearance | Yellow crystalline powder |
| Odor | Odorless |
| Density | Density: 1.4 g/cm3 |
| Solubility in water | soluble in water |
| log P | 0.1 |
| Acidity (pKa) | 6.68 |
| Basicity (pKb) | 9.0 |
| Magnetic susceptibility (χ) | -4.8 × 10⁻⁶ cm³/mol |
| Refractive index (nD) | 1.592 |
| Viscosity | Viscous oil |
| Dipole moment | 7.98 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 226.5 J·mol⁻¹·K⁻¹ |
| Pharmacology | |
| ATC code | B06AC05 |
| Hazards | |
| Main hazards | Causes skin irritation. Causes serious eye irritation. May cause respiratory irritation. |
| GHS labelling | GHS07, GHS09 |
| Pictograms | GHS07 |
| Signal word | Warning |
| Hazard statements | H302 + H312 + H332: Harmful if swallowed, in contact with skin or if inhaled. |
| Precautionary statements | Precautionary statements: P261, P264, P271, P272, P273, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362+P364, P403+P233, P405, P501 |
| Autoignition temperature | > 400 °C |
| LD50 (median dose) | LD50 (median dose): **NA** |
| PEL (Permissible) | Not established |
| REL (Recommended) | 5 mg |
| Related compounds | |
| Related compounds |
Benzoyl-arginine ethyl ester hydrochloride Nα-Benzoyl-L-arginine p-nitroanilide hydrochloride Nα-Benzoyl-DL-arginine amide hydrochloride Nα-Benzoyl-L-arginine methyl ester hydrochloride |
