| 摘要 |
<p>Dipeptides of formula (I) are new: x=2- or 4-OH, 4-NH2 or 4-OMe; y=-NH. CH-CO-; Z=-NH. CH(R1)-COOH; R=Me, H, -CHMe-Et or -CH2. CH(Me)2; R1=benzyl, opt. ring-substd. by OH; proviso: when X=OH or MeO, -Y-Z is not -NH.CH2CO.NH.CH(CH2Ph).COOH. - Specifically claimed are p-hydroxybenzyl -L-Ala-L-Phe; p-hydroxybenzoyl Gly-L-Tyr; o-hydroxybenzoyl -L-Ile-L-Phe; p-methoxy benzoyl-L-Leu-L-Phe, or p-aminobenzyl -L-Ala-L-Tyr. 3 Procedures are claimed (1) the substrate is incubated with (I), hippuricase (II), 4-amino-antipyrine (4-AAP) and an oxidising agent (e.g. HIO4) able to convert X-benzoic acid to a substance which reacts with 4-AAP to form a quinoneimine dye, the concn. of which determined colorimetrically; (2) the sample is incubated with (I), (II), NADPH or NADH, and a benzoate hydroxylase (depending on the nature and position of X), then measuring the decrease in absorbance at 340nm; (3) the substrate is incubated with (I; X2NH2) and (II), then NaNO2 added and the resulting diazonium salt coupled (e.g. to 1-naphthol-2-sulphonic acid) to form a dye, the concn. of which is determined colorimetrically.</p> |
