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PubMed1997

Effect of partially modified retro-inverso analogues derived from C-reactive protein on the induction of nitric oxide synthesis in peritoneal macrophages.

1. The ability of three modified tetrapeptides, representing fragments of the C-reactive protein (CRP) sequence and stabilized in the first peptide bond by retro-inverso modification, to affect the secretion of nitric oxide (NO) was studied in macrophages of BALB/c mice. 2. These tetrapeptides, resembling the aminoacid sequence of tuftsin (CRP 1, H-gThr-(R,S)mLys-Pro-Leu-OH, ITF 1192; CRP II, H-gGly-(R, S)mLys-Pro-Arg-OH, ITF 1127; CRP III, H-gThr-(R,S)mLys-Pro-Gln-OH. ITF 1193), were able to induce NO synthesis by peritoneal macrophages in a dose-dependent manner; the most stimulating dose was 1000 ng ml-1 for CRP II and 100 ng ml-1 for CRP I and CRP III. NO synthesis was not strictly dependent on lipopolysaccharide (LPS) activation. 3. The enhanced effect of retro-inverso CRP-related analogues on the expression of iNOS (inducible NO synthase) was confirmed by higher levels of iNOS activity in the cytosol and by the increase in iNOS protein, as evaluated by Western blot analysis, in macrophages stimulated by CPR compared with untreated ones. 4. The production of NO by retro-inverso CRP-peptide analogues was significantly inhibited by dexamethasone (20 microM), NG-monomethyl-L-arginine (L-NMMA) (500 microM) and pyrrolidine dithiocarbamate (PDTC) (100 microM). 5. Retro-inverso CRP-peptide analogues stimulated macrophages to produce high levels of interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF-alpha) in the presence of LPS. 6. Retro-inverso CRP-peptide analogues stimulated NO synthesis by the enhancement of endogenously produced IL-1 and TNF-alpha, as the treatment of peritoneal macrophages with LPS in the presence of neutralizing anti-IL-1 and anti-TNF monoclonal antibodies (mAbs) reduced retro-inverso analogue-induced NO secretion. Data indicate a predominant role for IL-1 alpha in the induction of NO secretion by retro-inverso analogues. 7. These results suggest that retro-inverso CRP derived analogues act as costimulators of NO and cytokine synthesis in macrophages. The mechanisms by which they cause iNOS induction appear to be strongly dependent on the activation of nuclear factor-kappa B (NF-kappa B).

Animals↗
PubMed1983

Post-proline cleaving enzyme (prolyl endopeptidase) from bovine brain.

A post-proline cleaving enzyme [prolyl endopeptidase, EC 3.4.21.26] was purified about 3,700-fold from an extract of bovine brain by a series of column chromatographies on DEAE-Sephadex, hydroxyapatite and PCMB-T-Sepharose, and gel filtration on Sephadex G-200 using N-carbobenzoxy-Gly-Pro-beta-naphthylamide (Z-Gly-Pro-2-NNap), thyrotropin releasing hormone (TRH) and oxytocin as substrates. The purified enzyme appeared homogeneous as judged by disc gel and SDS gel electrophoreses. The enzyme was most active at pH 7.5 and 7.2 with Z-Gly-Pro-2-NNap and TRH, respectively, and hydrolyzed peptide bonds involving Pro-X (X=amino acid, peptide, ester and amide) bonds of synthetic substrates, oxytocin, vasopressin, neurotensin, substance P, tuftsin, bradykinin, and insulin B chain. However, the enzyme was inert toward collagen, gelatin, and casein. The enzyme was completely inactivated by diisopropylphosphorofluoridate (DFP), Z-Gly-Pro-chloromethyl ketone and p-chloromercuribenzoate (PCMB), while it was not inhibited by phenylmethane sulfonylfluoride (PMSF) or metal chelators. Determination of the amino acid composition revealed that the enzyme contained 25 half-cystines. Modification of three cysteine residues of the enzyme by PCMB led to complete inactivation. The isoelectric point of the enzyme was 4.8, and the molecular weight was estimated to be 76,000 by ultracentrifugal analysis and 75,000-74,000 by both gel filtration and sodium dodecyl sulfate (SDS) gel electrophoresis, suggesting that the enzyme is present as a monomer. These results indicate that the post-proline cleaving enzyme from bovine brain is very similar to those previously purified from lamb brain and kidney in its enzymatic properties, substrate specificity and physicochemical properties, in sharp contrast with the results obtained by Tate, who reported that the bovine brain prolyl endopeptidase was inert toward oxytocin, vasopressin and bradykinin.

Amino Acid Sequence↗
PubMed1979

Facile thiolytic removal of the o-nitrophenylsulphenyl amino-protecting group.

2-Mercaptopyridine was used to effect the selective, mild and efficient cleavage of the o-nitrophenylsulphenyl amino-protecting group from several amino acids and peptides. By utilization of this reagent a stepwise synthesis of the tetrapeptide Thr-Lys-Leu-Arg([Leu3]tuftsin) was successfully achieved. The potential use of 2-mercaptopyridine in mechanized peptide synthesis via the polymeric reagents approach is discussed.

Amino Acids↗
PubMed1994

Computational molecular modeling in peptide drug design.

The review concentrates on practical applications of computer molecular modeling in peptide drug design. The examples of the predictions (successful or not) made by computational modeling before synthesis of peptide analogs, not the explanations provided after synthesis and biological testing of peptides, are discussed. The review spans over 20 years of predictions made by computer molecular modeling for bradykinin, angiotensin, thyrotropin-releasing factor, tuftsin, substance P, CCK-related peptides, luliberin, alpha-melanotropin and opioid peptides. The described examples are discussed in terms of finding the optimal way to use computer modeling for peptide design. The step-by-step 'technology' of peptide design is outlined in detail.

Amino Acid Sequence↗
PubMed1987

HLAMP--a conjugate of hippuryllysine and AMP which contains a phosphoamide bond--stimulates chemotaxis in Dictyostelium discoideum.

A conjugate of hippuryllysine (HP) and adenylic acid was synthesized and purified. The structure of the conjugate, hippuryllysyl(N-epsilon-5'-phospho)adenosine (HLAMP) was established using 31P nuclear magnetic resonance, UV spectroscopy, acid/base lability, and enzyme digestion with AMP deaminase, alkaline phosphatase, 5'-nucleotidase, and a phosphoamidase activity recently identified in Dictyostelium discoideum. The results indicate that HLAMP contains a phosphoamide bond between the phosphate of AMP and the epsilon amino group of HL. Employing a microdroplet assay to assess chemotactic activity, HLAMP was found to be a potent chemoattractant of 7-h developing amoebae of D. discoideum. Other conjugates, including lysine-AMP (LAMP), tuftsin-AMP (TAMP) and avidin-AMP (AVAMP), as well as the degradation products of HLAMP (HL, AMP, and lysine) exhibited no chemotactic activity. The molecular structure of HLAMP is compared to that of other known chemoattractants of the cellular slime molds, and possible chemotactic receptors for HLAMP are considered.

Chemotaxis↗
PubMed1981

Purification and properties of a bovine brain thyrotropin-releasing-factor deamidase. A post-proline cleaving enzyme of limited specificity.

A bovine brain thyrotropin-releasing-factor (thyroliberin) deamidase has been purified 1100-fold to apparent homogeneity. Molecular weight estimates by gel filtration and sodium dodecylsulfate gel electrophoresis indicate that the enzyme consists of a single polypeptide chain of molecular weight of about 62 000-65 000. The enzyme is inactivated by sulfhydryl blocking agents. Serine proteinase inhibitors, phenylmethanesulfonyl fluoride and benzamidine, have no effect. Besides thyroliberin, the enzyme hydrolyzes peptide bonds involving the carboxyl group of proline residues in luliberin, tuftsin, angiotensin II, melanotropin, and neurotensin. Oxytocin, vasopressin, and bradykinin are not cleaved; they are, however, strong competitive inhibitors of thyroliberin deamidation. The specificity studies indicate that the enzyme is a "post-proline cleaving enzyme" which hydrolyzes peptides of the general structure, Yaa-Pro-Xaa, in which Xaa = amino acid, peptide, or amide (not Pro), and Yaa = N-blocked basic amino acid or a peptide sequence in which the C-terminal residue (i.e. the residue prior to Pro) is a basic amino acid such as His, Lys, or Arg. The enzyme is compared to other post-proline cleaving enzymes.

Amidohydrolases↗
PubMed1981

Monocyte cytotoxicity after splenectomy.

Antibody-dependent cell-mediated cytotoxicity (ADCC) by monocytes was determined in 45 adults approximately 4 years after splenectomy for either abdominal trauma or accidental injury during operation for benign gastroduodenal ulcer. Compared to controls, both groups of splenectomized persons showed increased numbers of monocytes and decreased monocyte ADCC. The decrease of monocyte ADCC was only significant in those splenectomized persons in whom accessory splenic tissue was not detectable by isotope scanning. Addition of the spleen-dependent peptide tuftsin to monocytes in vitro did not augment their ADCC. An increase serum concentration of immune complexes was neither related to the presence of splenic tissue nor to the monocyte cytotoxicity. Vaccination with pneumococcal polysaccharide had no effect on monocyte ADCC. It is suggested that the defective monocyte cytotoxicity observed in splenectomized persons without detectable splenic tissue might be relevant to post splenectomy infectious susceptibility.

Adult↗
PubMed1982

Cationic polyelectrolytes, liquoid and leukocyte extract modulate the binding of IgG to group A streptococcal Fc-receptors.

Various polyelectrolytes were investigated regarding their capacity to inhibit the binding of human IgG to Fc-receptors on group A streptococci, type M1. Of cationic substances, protamine and arginine-rich histone inhibited significantly, while lysine-rich histone, concanavalin A, lysozyme, polymyxin B, ribonuclease and tuftsin did not. Of anionic materials, liquoid was inhibitory, in contrast to chondroitin sulphate, dextran sulphate, DNA and heparin. Washing experiments showed that the inhibition was caused by binding of the polyelectrolytes to the streptococci. The finding that heated IgG inhibited the binding of histone to the streptococci also indicated a close relation between the binding sites for these compounds. Diffusion-in-gel experiments with alkaline extract of M1 demonstrated that the substances blocking the IgG Fc-receptor were bound to polyglycerophosphate, suggesting that the inhibition of the IgG uptake was due to interaction with lipoteichoic acid. Leukocyte and platelet extracts could modify the binding of IgG, probably by an enzymatic digestion of the receptors. The arginine-rich histone was also capable of inhibiting the binding of IgG to type M15 group A streptococci and to one group G strain. However, the polyelectrolytes had no effect on the binding of IgG to Staphylococcus aureus or of IgA to type 4 group A streptococci.

Anions↗
PubMed1982

The effects of substance P on histamine and 5-hydroxytryptamine release in the rat.

1. Substance P (SP) induces histamine release from isolated rat peritoneal mast cells at concentrations of 0.1-10 muM.2. Inhibitors of glycolysis and oxidative phosphorylation prevent the release of histamine induced by SP.3. Cells heated to 47 degrees C for 20 min release histamine when treated with an agent causing cell lysis but fail to release in response to SP.4. SP does not release histamine by interacting with cell-bound IgE.5. Histamine release by SP is rapid, with more than 90% of the response occurring within 1 min of the addition of the peptide to mast cells at 37 degrees C.6. Substance P, unlike antigen-antibody or compound 48/80, does not show enhanced release of histamine when calcium (0.1-1 mM) is present in the extracellular medium but calcium increases the response to SP when the ion is added after the peptide. Extracellular calcium (0.1-1 mM), magnesium (1-10 mM) and cobalt (0.01-0.1 mM) all inhibit SP-induced histamine release when added before the peptide. Pre-treatment of the cells with EDTA (10 mM) and washing in calcium-free medium inhibits the histamine release induced by SP.7. Histamine release induced by SP was optimum at an extracellular pH of 7.2.8. A number of peptides structurally related to SP were examined for histamine-releasing activity. At the concentrations tested, the N-terminal dipeptides Lys-Pro and Arg-Pro, tuftsin, physalaemin, eledoisin, SP(3-11), SP(4-11) and [p-Glu(6), p-amino Phe(7)]-SP(6-11) were all found to be inactive. The relative activities of the other peptides were: [Formula: see text]9. Rat basophilic leukaemia cells (RBL-2H3) fail to respond to SP at concentrations which activate rat mast cells. Release of 5-hydroxytryptamine by immunological activation of RBL cells is not changed by the presence of SP.10. The mechanism of action of SP on mast cells and the nature of the SP receptor on mast cells is discussed in relation to SP receptors in other cell types.

Animals↗
PubMed1975

Chemical modulation of diphtheria toxin action on cultured mammalian cells.

Ammonium chloride (4 times 10-3 M) rendered HEp-2 monolayers completely insensitive to the action of diphtheria toxin, as measured by de novo protein synthesis. Total protection was observed even with large amounts of toxin (400 minimum lethal doses/ml). Ammonium chloride did not reduce toxicity by direct action on the protein, nor did it prevent the adsorption of toxin to the cell membrane. Although the ammonium salt did not block the initial interaction between cell and toxin, it did maintain the toxin at a site amenable to neutralization with antitoxin. Surface-adsorbed toxin was inactivated by cellular enzymes or alternatively was desorbed from the membrane during a 12-h incubation in the presence of ammonium chloride. In addition, ammonium chloride provided protection to both toxin-sensitive guinea pig peritoneal macrophages and a partially toxin-resistant strain of HEp-2 cells. Sodium arsenite was effective in protecting cell monolayers from the action of diphtheria toxin; unlike ammonium chloride, its action was not dependent upon continued incubation with cells during exposure to toxin. Inhibitors of energy metabolism abolished toxin action either totally (sodium fluoride) or partially (dinitrophenol and sodium cyanide). Inhibitors of cellular proteases, on the other hand, did not modify toxin activity. The ability of several modifiers of membrane function to alter expression of toxicity for HEp-2 cells was also examined. One compound known to enhance endocytic activity, Tuftsin, had no effect, whereas poly-L-ornithine provided partial protection. Of the two compounds known to alter membrane fluidity, cytochalasin B provided partial protection for HEp-2 cell cultures, whereas colchicine had no effect. Agents that bind to sulfhydryl groups on the cell surface had no apparent effect on toxicity, suggesting that the initial toxin-cell interaction does not involve sulfhydryl groups. Those compounds that provide virtually full protection against the action of diphtheria toxic on cell monolayers (i.e., ammonium chloride, sodium fluoride, and sodium arsenite) had no inhibitory effect on the in vitro enzyme activity associated with fragment A of the toxin.

Ammonium Chloride↗
PubMed1988

Purification and characterization of an arginine-specific carboxypeptidase from Mycoplasma salivarium.

The carboxypeptidase which had been shown to be present exclusively in nonfermentative mycoplasmas was found to be associated with cell membranes of Mycoplasma salivarium. The enzyme was released from the membranes with Triton X-100 and purified by ion-exchange chromatography on DEAE-Sephacel, affinity chromatography on arginine-Sepharose 4B, and chromatofocusing. The purified enzyme had a molecular mass of 218 kilodaltons, as estimated by gel filtration through Sepharose CL-6B, and yielded one band of activity in analytical disc-polyacrylamide gel electrophoresis performed in the presence of 0.5% (wt/vol) Triton X-100. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme treated in the presence or absence of 2-mercaptoethanol revealed one band with a molecular mass of 87 kilodaltons. The enzyme catalyzed selectively the cleavage of the C-terminal arginine residue of peptides such as N-benzoylglycyl-L-arginine, tuftsin, and bradykinin and was inhibited considerably by o-phenanthroline and EDTA but only slightly by NiCl2. The inhibition of the enzyme by EDTA was fully reversed by the addition of ZnCl2, whereas the addition of CoCl2 activated the enzyme.

Arginine↗
PubMed1986

Structural requirement for the recognition of luteinizing hormone releasing hormone (LHRH) by monoclonal and conventional anti-LHRH antibodies.

Immunochemical studies on monoclonal and conventional anti-LHRH antibodies have been reported. The association constants (Ka) were in the order of 10(9)-10(10) L/mol when calculated from Scatchard and Steward-Petty plots. Heterogeneity indices (a) calculated from Sips plot were nearly 1.0, indicating the homogeneous nature of monoclonals. Most of the conventional anti-LHRH produced by monkey, baboon, rabbit, and dog, by immunization using LHRH linked to tetanus toxoid by the carbodiimide condensation method, showed a single slope in Scatchard analysis (except two dog antisera) and a values were nearly 1.0. Monoclonals and conventionals reacted most strongly with native LHRH(NH2). Monoclonals showed poor reactivity with LHRH free acid and LHRH fragments containing free acid. The C-terminus tetrapeptide 7-10 showed 10 times more reactivity than tripeptide 4-6. The heptapeptide 4-10 showed 100 and 1000 times more reactivity than the tetra- and tri-peptide, respectively. Introduction of the tripeptide pGlu-His-Trp-OH to heptapeptide 4-10 caused five times more inhibition in reactivity than the heptapeptide. Conventional anti-LHRH antibodies manifested specificity to the C-terminus of LHRH. These sera did not react with LHRH free acid and LHRH fragments of sequence 4-6, 7-10, and 4-10. The complete loss of reactivity of conventional antibodies and poor reactivity of monoclonal antibodies was partly regained when LHRH free acid was coupled to Lys, Lys-MDP, or (Ala)2-tuftsin, suggesting that for monoclonals and conventionals the antigenic determinant was confined to the conformation involving the C-terminus amide of LHRH.

Amides↗
PubMed1987

The immunopharmacology of immunotoxicology, and immunorestoration.

The first part of this paper focuses on the secondary immunodeficiencies caused by immunosuppressive drugs and environmental chemicals. The mechanism of action and the therapeutic effects of azathioprine, glucocorticosteroids, cyclophosphamide, cyclosporin A, and anticancer drugs will be discussed. The immunotoxic actions of benzene, polychlorinated and polybrominated biphenyls, tetrachlorodibenzo-paradioxin, polycyclic aromatic hydrocarbons, various insecticides, metals and abused drugs or drugs with side effects are also described. Immunorestorative approaches are discussed in the second part, based on our current knowledge of the immune system and the lymphokines and hormones involved in its function. The usefulness of thymic hormones, interleukin 2, macrophage growth factor/colony stimulating factor, and interferons as immunotherapeutic agents is considered. In addition, we address chemically defined drugs, such as levamisole, diethyldithiocarbamate, isoprinosine, muramyl dipeptides, azimexon, ciamexon, bestatin, tuftsin, and pyrimidinoles, and finally conclude that combined use of different immunostimulants may be the most effective way to treat the above mentioned immunodeficiencies.

Adjuvants, Immunologic↗
PubMed1983

Binding and phagocytosis of sialidase-treated rat erythrocytes by a mechanism independent of opsonins.

Rat peritoneal macrophages bind and phagocytoze homologous sialidase-treated erythrocytes at a rate which is dependent on the amount of sialic acid that has been removed from the cells. Increased binding of erythrocytes is observed after the removal of 10-20% of membrane sialic acid, while for phagocytosis at least 30-40% of this substance must be removed. With Vibrio cholerae sialidase only a partial (80%) hydrolysis of rat erythrocyte sialic acid is possible, whereas Arthrobacter ureafaciens sialidase leads to complete desialylation and therefore causes stronger binding and phagocytosis of the erythrocytes than the V. cholerae enzyme. Preincubation of peritoneal macrophages with sialidase impairs binding and phagocytosis. Experiments were performed to account for the stimulation of binding and phagocytosis observed in the presence of native, homologous serum. However, an involvement of immunoglobulins and complement factors of the classical and alternative pathway in the engulfment process has been excluded. Fibronectin, tuftsin and substance P have no influence, either. On the other hand, peanut agglutinin and Erythrina crystagalli agglutinin are potent stimulators of binding and phagocytosis of sialidase-treated erythrocytes, whereas soybean agglutinin has only little and limulin no influence at all. It is concluded that sialidase-treated erythrocytes, having been bound to the beta-galactose-specific lectin on the macrophage surface, are phagocytozed as a function of their number and binding strength to the macrophages. The influence of native serum and especially of the plant lectins on this process is discussed.

Animals↗
PubMed1985

In vitro stimulation of macrophages by quadrol [N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine].

Mouse peritoneal macrophages, when exposed to Quadrol [N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine] in vitro, show a dose dependent enhanced spreading over a four-hour period. In vitro Quadrol induced phagocytosis of polystyrene beads was found to be time and concentration dependent. The rate and extent of the enhancement of phagocytosis was comparable to that observed for lipopolysaccharide and tuftsin.

Animals↗
PubMed2001

Evaluation of 99mTc-RP128 as a potential inflammation imaging agent: human dosimetry and first clinical results.

UNLABELLED: 99mTc-RP128 is a bifunctional peptide chelate designed to target the tuftsin receptor, expressed by neutrophils, monocytes, and macrophages. Studies in animal models of both infectious and noninfectious inflammation have shown a positive correlation between accumulation of 99mTc-RP128 and quantitative measures of inflammation. A phase 1 trial was conducted with the objective of determining the safety, biodistribution, and human dosimetry of 99mTc-RP128 in eight healthy volunteers. For evaluation of the potential of 99mTc-RP128 for imaging sites of inflammation, 10 patients with active rheumatoid arthritis were studied. METHODS: Normal biodistribution was determined using the conjugate view method up to 24 h after intravenous injection of 280 MBq 99mTc-RP128. Dosimetry calculations were based on standard MIRD methodology, using the International Commission on Radiological Protection model 30 of the gastrointestinal tract and a voiding bladder model with an interval of 4.8 h. For rheumatoid arthritis patients, whole-body scans and spot views of the hands, knees, and feet were obtained at 1 and 3 h after injection of 475 MBq 99mTc-RP128. RESULTS: 99mTc-RP128 was cleared rapidly from the blood by renal excretion, and no major organs showed significant accumulation. The synovia of the major joints were visualized for all subjects. The effective dose equivalent and the effective dose were calculated to be 0.011 and 0.0094 mSv/MBq, respectively. The highest dose was to the bladder wall, which received 0.076 mGy/MBq. In all rheumatoid arthritis patients, we observed a markedly increased uptake in several affected joints. Painful and swollen joints were detected with a sensitivity of 76% and 69%, respectively. Seventy-three percent of the joints with radiographic signs of erosion were scintigraphically positive. In some patients, lines of increased activity were observed and were considered to correspond to uptake in the synovium lining tendon sheaths in the wrists and hands. CONCLUSION: This study shows that 99mTc-RP128 is safe and can successfully be used to visualize clinically affected joints in patients with long-standing rheumatoid arthritis. A proposed radioactive dose of 450-500 MBq will produce an effective dose well within the range of effective doses for commonly used radiopharmaceuticals.

Adult↗
PubMed2000

Foreign body sarcoma: effects of foreign DNA, beta-carotene and paprika applied to the implant surface.

Sarcoma arises extremely rarely on foreign bodies in man, but is aggressive and often lethal. A coating for implants which would further reduce the risk in man is desirable. The incidence in mice is much greater, and responds to chemical treatment of the implant surface. Coating with histones increases tumour yield. Accordingly, related substances, foreign DNA, DNase and a mixture of the two, were tested for anticancer activity by application to 25 mm nitrocellulose filters in groups of 30-45 BALB/c mice, in comparison with untreated filters. Other substances reported to influence neoplasia, paprika, beta-carotene, rhodamine and tuftsin; and substances expected to be neutral, oxyprenolol, liquid paraffin, iodine, and adenosine diphosphate were similarly tested against concurrent untreated controls for comparison. Bovine DNA (p = 0.01) and DNA/DNase mixture (p = 0.04) and DNase fomented tumour growth by 55, 45 and 59% respectively. Paprika and beta-carotene did so by 70% (p = 0.05). The other substances were inert. None were candidates for an anti-sarcoma coating.

Animals↗
PubMed1992

Chemical modification of the monkey brain cytosolic aminopeptidase that cleaves enkephalin to its constituent amino acids. Evidence for essential tyrosine residue (residues).

A cytosolic monkey brain aminopeptidase is known to cleave amino acids sequentially from the amino termini of peptides like enkephalins, angiotensins, and tuftsin. This enzyme is stimulated by ATP-Mg2+ and inactivated by cyclic AMP-dependent phosphorylation. Chemical modification of this aminopeptidase by several amino acid-modifying agents indicated essential lysine, histidine, arginine, cysteine, and tyrosine residues. The involvement of tyrosine residues in the catalytic activity was confirmed by modification by N-acetylimidazole and acetic anhydride, hydroxylamine treatment, and absorbance studies. Moreover, acetic-1-14C anhydride could label the enzyme that was inhibited by ATP or by bestatin, a competitive inhibitor of the enzyme.

Acetic Anhydrides↗