Divalent copper was found to inhibit non-competitively the lysis of Micrococcus lysodeikticus cells by hen egg-white lysozyme, with an inhibition constant K, = 3.8 X lo2 M-l. The association constants of Cu2+ for lysozyme and for a derivative of lysozyme in which tryptophan residue 108 was selectively modified, were measured spectrofluorimetrically and found to be 1.8 X lo2 M-l and 1.0 X lo3 M-...

Three new rimantadine Schiff bases (RSBs) were prepared, and then the interaction of RSBs with bovine serum albumin (BSA) was investigated using fluorescence, synchronous fluorescence, UV-vis absorption spectroscopy under physiological conditions. The results showed that the three RSBs effectively quenched the intrinsic fluorescence of BSA via static quenching. Binding constant (Ka), number of ...

Three new rimantadine Schiff bases (RSBs) were prepared, and then the interaction of RSBs with bovine serum albumin (BSA) was investigated using fluorescence, synchronous fluorescence, UV-vis absorption spectroscopy under physiological conditions. The results showed that the three RSBs effectively quenched the intrinsic fluorescence of BSA via static quenching. Binding constant (Ka), number of ...

The characteristics of tryptophan uptake in isolated human placental brush-border membrane vesicles were investigated. Tryptophan uptake in these vesicles was predominantly Na+-independent. Uptake of tryptophan as measured with short incubations occurred exclusively by a carrier-mediated process, but significant binding of this amino acid to the membrane vesicles was observed with longer incuba...

background and objectives: the essential amino acid l-tryptophan can be produced by a condensation reaction between indole and l-serine, catalyzed by b. subtilis with tryptophan synthase activity. application of the tryptophan is widespread in the biotechnology domain and is sometimes added to feed products as a food fortifier. materials and methods: the optimum concentration of the iranian can...

Glyoxalase I from human erythrocytes was studied by use of the strong reversible competitive inhibitor S-p-bromobenzylglutathione. Replacements of cobalt, manganese and magnesium for the essential zinc in the enzyme were made by a new procedure involving 10% methanol as a stabilizer of the enzyme. The K(m) value for the adduct of methylglyoxal and glutathione was essentially unchanged by the me...

Two vitamin B6 derivatives, N-bromoacetylpyridoxamine (BAPM) and its phosphate ester have been found to be affinity-labeling reagents for mitochondrial aspartate aminotransferase (EC 2.6.1.1). These derivatives were first shown to react with a critical sulfhydryl group in tryptophan synthase (Higgins, W., and Miles, E. W. (1978) J. Biol. Chem. 253, 4648-4652). In the apoaminotransferase, BAPM h...

Growth of animals receiving diets low in protein and nicotinic acid may be retarded by the addition of corn products (l-4), of certain amino acids (5-9), or of proteins deficient in tryptophan (8-11). This inhibition, which is obtained with diets relatively deficient in tryptophan, can be overcome by the administration of nicotinic acid or of tryptophan (l-11). It has been suggested that this d...

Objective: Interferon-α (IFN) therapy can cause depressive symptom which may lead to drug discontinuation. By interfering with tryptophan pathway, the available level of tryptophan required for serotonin synthesis decreases which could be related to depression. The aim of this study was to evaluate whether soybean diet could improve IFN-induced depression. Materials and Methods: Male mice weigh...