scholarly journals Products of aminolysis and enzymic hydrolysis of the cephalosporins

1970 ◽  
Vol 116 (3) ◽  
pp. 371-384 ◽  
Author(s):  
J. M. T. Hamilton-Miller ◽  
G. G. F. Newton ◽  
E. P. Abraham
Keyword(s):  
Amino Acids ◽  
Aqueous Solutions ◽  
Physical Properties ◽  
Side Chain ◽  
Enzymic Hydrolysis ◽  
Weakly Alkaline ◽  
Immunological Properties ◽  
Amino Compounds ◽  
Lactam Ring ◽  
Hydrolysis Of

1. The reaction of cephalosporins with ammonia, amino acids and other simple amino compounds in weakly alkaline aqueous solutions yields labile compounds with λmax. 230nm. The reaction of deacetyl- and deacetoxy-cephalosporins under similar conditions yields compounds with λmax. 260nm. 2. Hydrolysis with a β-lactamase results in the formation of compounds with λmax. 230nm from deacetylcephalosporins and cephalosporins, but not from deacetoxycephalosporins. 3. These different compounds decompose to give penaldates and penamaldates derived from the side chain and the carbon atoms of the β-lactam ring. 4. Derivatives similar to those obtained with simple amino compounds appear to be formed when cephalosporins and their analogues react with lysine polymers. 5. Some of the chemical and physical properties of the various derivatives have been studied and tentative structures for them are proposed. 6. Possible implications of the results in relation to the immunological properties of the cephalosporins are discussed.

Covalent attachment of amino acids to casein. 1. Chemical modification and rates of in vitro enzymic hydrolysis of derivatives

1979 ◽  
Vol 27 (5) ◽  
pp. 1098-1104 ◽  
Author(s):  
Antoine J. Puigserver ◽  
Lourminia C. Sen ◽  
Elvira Gonzales-Flores ◽  
Robert E. Feeney ◽  
John R. Whitaker
Keyword(s):  
Amino Acids ◽  
Chemical Modification ◽  
Covalent Attachment ◽  
Enzymic Hydrolysis ◽  
Hydrolysis Of

Modeling solubility and acid-base properties of some polar side chain amino acids in NaCl and (CH 3 ) 4 NCl aqueous solutions at different ionic strengths and temperatures

2018 ◽  
Vol 459 ◽  
pp. 51-64 ◽  
Author(s):  
Clemente Bretti ◽  
Rosalia Maria Cigala ◽  
Ottavia Giuffrè ◽  
Gabriele Lando ◽  
Silvio Sammartano
Keyword(s):  
Amino Acids ◽  
Aqueous Solutions ◽  
Side Chain ◽  
Acid Base ◽  
Base Properties

Asymmetric Synthesis of Enantiomerically Enriched a-Amino Acids Containing 2-Furyl- and 2-Thienyl-1,2,4-triazoles in the Side-Chain

2014 ◽  
Vol 69 (4) ◽  
pp. 451-460 ◽  
Author(s):  
Ashot S. Saghyan ◽  
Hayarpi M. Simonyan ◽  
Satenik G. Petrosyan ◽  
Anna F. Mkrtchyan ◽  
Lilit V. Khachatryan ◽  
...  
Keyword(s):  
Amino Acids ◽  
Schiff Base ◽  
Asymmetric Synthesis ◽  
Efficient Method ◽  
Enantiomeric Excess ◽  
Side Chain ◽  
Chiral Auxiliaries ◽  
Enantiomerically Pure ◽  
Dehydroamino Acids ◽  
Hydrolysis Of

An efficient method for the asymmetric synthesis of a-amino acids, containing furyl- and thiophenyl-substituted triazoles in their side-chain, is reported. The strategy relies on Michael addition of 3,4,5-substituted 1,2,4-triazoles to the C=C bond of chiral NiII complexes containing the Schiff base formed from dehydroamino acids (dehydroalanine and (E + Z)-dehydroaminobutyric acid) and from chiral auxiliaries, i. e. (S)-2-N-(N0-benzylprolyl)aminobenzophenone and (S)-2-N- (N0-2-chlorobenzylprolyl) aminobenzophenone. The reactions proceeded with good to very good diastereoselectivity. Hydrolysis of the diastereomeric mixtures of metal complexes afforded the enantiomerically pure a-amino acids with high enantiomeric excess (ee> 98%).

scholarly journals Changes in proton-magnetic-resonance spectra during aminolysis and enzymic hydrolysis of cephalosporins

1970 ◽  
Vol 116 (3) ◽  
pp. 385-395 ◽  
Author(s):  
J. M. T. Hamilton-Miller ◽  
Eva Richards ◽  
E. P. Abraham
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Structural Changes ◽  
Ring Structure ◽  
Reaction Products ◽  
Enzymic Hydrolysis ◽  
Lactam Ring ◽  
Group 5 ◽  
Hydrolysis Of ◽  
Magnetic Resonance Spectra

1. Changes in proton-magnetic-resonance spectra were followed during the reaction of cephalosporins, deacetylcephalosporins, deacetoxycephalosporins and a Δ2-cephalosporin with ND3 in D2O. 2. Changes in proton-magnetic-resonance spectra were also followed during the hydrolysis of a cephalosporin and a deacetylcephalosporin in D2O with a β-lactamase. 3. Structures for the reaction products are proposed. 4. The signals obtained after aminolysis of the β-lactam ring of a cephalosporin indicate that the reaction is accompanied by expulsion of the acetoxy group as acetate, formation of a double bond in the Δ4-position and the appearance of an exocyclic methylene group. 5. Aminolysis of deacetyl- and deacetoxycephalosporins can occur without immediate structural changes in the dihydrothiazine ring. 6. In contrast, the ring structure of the first product of enzymic hydrolysis of a deacetylcephalosporin is apparently identical with that of the product of aminolysis of the cephalosporin itself.

Reversible Inhibition of Carboxypeptidase A. IV. Inhibition of Specific Esterase Activity by Hippuric Acid and Related Species and other Amino Acid Derivatives and a Comparison with Substrate Inhibition

1975 ◽  
Vol 53 (13) ◽  
pp. 1993-2004 ◽  
Author(s):  
John W. Bunting ◽  
Chester D. Myers
Keyword(s):  
Amino Acids ◽  
Hippuric Acid ◽  
Substrate Inhibition ◽  
Enzymic Hydrolysis ◽  
Carboxypeptidase A ◽  
Phenyllactic Acid ◽  
Peptide Substrates ◽  
Uncompetitive Inhibition ◽  
Hydrolysis Of ◽  
Noncompetitive Inhibitors

The anions of each of the following carboxylic acids exhibit uncompetitive inhibition of the hydrolysis of O-hippuryl-L-3-phenyllactic acid by bovine carboxypeptidase A at pH 7.5, 25°, ionic strength 0.2: hippuric acid, p-chloro- and p-nitrohippuric acids, hippurylglycine, carbobenzoxyglycine, phenaceturic acid, N'-(3-phenylpropanoyl)glycine, benzoxyacetic acid, 3-benzoylpropanoic acid, and O-hippuryl-D-mandelic acid. In each case, this uncompetitive inhibition is consistent with the ordered binding of substrate and inhibitor to the enzyme; i.e. the inhibitor binds to E.S but not to the free enzyme. Evidence is presented for the binding site for uncompetitive inhibitors being the same as for inhibitory ester substrate molecules. Comparison of the specificities of uncompetitive inhibitors and esters which display substrate inhibition provides evidence for a critical conformational change which controls the binding of uncompetitive inhibitors and inhibitory substrate molecules.D-Phenylalanine, D-leucine, D-p-nitrophenylalanine, glycyl-L-tyrosine, glycyl-L-phenylalanine, and glycyl-L-leucine are competitive inhibitors of the enzymic hydrolysis of O-hippuryl-L-3-phenyllactic acid, whereas the N-chloroacetyl derivatives of L-tyrosine, L-phenylalanine, and L-leucine are noncompetitive inhibitors. For the above D-amino acids, glycyl dipeptides, and N-chloroacetyl amino acids, the phenylalanine derivative in each case is a considerably stronger inhibitor than the corresponding leucine derivative. This preference is similar to that observed for the binding of peptide substrates but the reverse of that observed for ester substrates and simple mono- and dicarboxylate ion inhibitors.The peptide substrates carbobenzoxyglycylglycyl-L-phenylalanine and N-chloroacetyl-L-phenylalanine are noncompetitive inhibitors of the enzymic hydrolysis of O-hippuryl-L-3-phenyllactic acid. This clearly demonstrates the presence of different ester and peptide binding sites in this enzyme, which is consistent with conclusions from recent studies in other laboratories.

scholarly journals The acid and enzymic hydrolysis of O-acetylated sialic acid residues from rabbit Tamm–Horsfall glycoprotein

1972 ◽  
Vol 129 (3) ◽  
pp. 683-693 ◽  
Author(s):  
A. Neuberger ◽  
Wendy A. Ratcliffe
Keyword(s):  
Sialic Acid ◽  
Vibrio Cholerae ◽  
Clostridium Perfringens ◽  
Slow Rate ◽  
Alkaline Treatment ◽  
Side Chain ◽  
Hydroxyl Groups ◽  
Enzymic Hydrolysis ◽  
Hydrolysis Of

Rabbit Tamm–Horsfall glycoprotein and bovine submaxillary glycoprotein were both found to contain sialic acid residues which are released at a slow rate by the standard conditions of acid hydrolysis. These residues are also resistant to neuraminidases from Vibrio cholerae and Clostridium perfringens. This behaviour was attributed to the presence of O-acetylated sialic acid, since the removal of O-acetyl groups by mild alkaline treatment normalized the subsequent release of sialic acid from rabbit Tamm–Horsfall glycoprotein by acid and by enzymic hydrolysis. Determination of the O-acetyl residues in rabbit Tamm–Horsfall glycoprotein indicated that on average two hydroxyl groups of sialic acid are O-acetylated, and these were located on the polyhydroxy side-chain of sialic acid or on C-4 and C-8. These findings confirm the assumption that certain O-acetylated forms of sialic acid are not substrates for bacterial neuraminidases. Several explanations have been suggested to explain the effect of O-acetylation of the side-chain on the rate of acidcatalysed hydrolysis of sialic acid residues.

scholarly journals The pH-dependence and group modification of β-lactamase I

1975 ◽  
Vol 149 (3) ◽  
pp. 547-551 ◽  
Author(s):  
S G Waley
Keyword(s):  
Ph Dependence ◽  
Water Soluble ◽  
Side Chain ◽  
Polar Group ◽  
Woodward’S Reagent K ◽  
Group Modification ◽  
Penicillanic Acid ◽  
Lactam Ring ◽  
Parameter Versus ◽  
Hydrolysis Of

The pH-dependence of the kinetic parameters for the hydrolysis of the β-lactam ring by β-lactamase I (penicillinase, EC 3.5.2.6) was studied. Benzylpenicillin and ampicillin (6-[D(-)-α-aminophenylacetamido]penicillanic acid) were used. Both kcat. and kcat./Km for both substrates gave bell-shaped plots of parameter versus pH. The pH-dependence of kcat./Km for the two substrates gave the same value (8.6) for the higher apparent pK, and so this value may characterize a group on the free enzyme; the lower apparent pK values were about 5(4.85 for benzylpenicillin, 5.4 for ampicillin). For benzylpenicillin both kcat. and kcat./Km depended on pH in exactly the same way. The value of Km for benzylpenicillin was thus independent of pH, suggesting that ionization of the enzyme's catalytically important groups does not affect binding of this substrate. The pH-dependence of kcat. for ampicillin differed, however, presumably because of the polar group in the side chain. The hypothesis that the pK5 group is a carboxyl group was tested. Three reagents that normally react preferentially with carboxyl groups inactivated the enzyme: the reagents were Woodward's reagent K, a water-soluble carbodi-imide, and triethyloxonium fluoroborate. These findings tend to support the idea that a carboxylate group plays a part in the action of β-lactamase I.

THE COMPOSITIONS OF SOME PEPTIDES PRODUCED BY AN ENZYMIC HYDROLYSIS OF WHEAT GLIADIN

1964 ◽  
Vol 42 (8) ◽  
pp. 1133-1140 ◽  
Author(s):  
A. J. Finlayson
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Enzymic Hydrolysis ◽  
Wheat Gliadin ◽  
Hydrolysis Of

Wheat gliadin was hydrolyzed extensively by treatment with pepsin and then by trypsin. A large number of peptides were produced as well as small amounts of some amino acids, thus indicating a substantial amount of hydrolysis of gliadin by the enzymes. Five peptides were obtained crystalline and two of these constitute 11.5% and 1.2% of gliadin, respectively. Their structures have been partly determined. The results indicate that wheat gliadin contains (Asp.Asp) bonds and at least 1.9% of the glutamic acid is present as glutamylglutamic acid.

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