L-alanine-glycine transminase in cunninghamella elegans

Cell-free extracts of Cunninghamella elegans catalyzed the formation of pyruvate and glycine from alanine and glyoxylate by alanine-glycine transaminase. The reversibility of the reaction was demonstrated. Optimum activity was obtained at pH 7.5 and 40C Km values for alanine, glyoxylate, pyruvate and glycine were 4.54, 4.34, 10.0 and 14.28 mM respectively. The only active transaminase involving L-alanine was the alanine-glycine enzyme. The extracts could not catalyze the transamination between L-alanine and either alpha-ketoglutarate or oxalacetate. D-Alanine was inactive. Addition of pyridoxal phosphate stimulated the transaminase activity, whereas hydroxylamine inhibited it. The inhibitory effect of hydroxylamine was reversed by pyridoxal phosphate

Differentiation between alanine-glutamate and alanine-glycine transaminase activities of penicillium martensii

Dialyzed cell-free extracts of Penicillium martensii contained, at the constitutive level, two different alanine transaminase catalyzing the formation of pyruvate and glutamate from alanine and alpha- oxoglutarate. The second was alanine-glycine from alanine and glyoxylate. The reversibility of the two reactions was demonstrated. Optimum activity of both enzymes occurred at pH 8.0 and 40C, but their temperature activity profiles and heat inactivation kinetics were different. The activity of the two enzymes was stimulated by addition of pyridoxal phosphate, whereas hydroxylamine inhibited it. The inhibition by hydroxylamine was overcome by pyridoxal phosphate

L-Serine dehydratase in some filamentous fungi II- comparative properties of L-Serine dehydratase of cunninghamella elegans and fusarium oxysporum

L-Serine dehydratase [EC 4.21.13] of Cunninghamella elegans and Fusarium oxysporum had a pH optimum of 8. Maximal activity of L- serine dehydratase of C. elegans occurred at 50C, while that of F. oxysporum enzyme was optimal at 40-50C. Both enzymes were thermolabile Km of C. elegans enzyme for L-Serine was 20 mM, whereas that of F. Oxysporum enzyme was 30 mM. The two enzymes were highly specific for L-Serine. The catalytic activity of both enzymes was inhibited by Zn2+, Cu2, Co2+, Mn2+ and Ca2+. No cofactor requirement was observed for both enzymes. L-Cysteine inhibited C. elegans enzyme competitively with a Ki of 0.87 mM and that of F. Oxysporum enzyme noncompetitively with a Ki of 3.81 mM

Partial purification, nature determination and some properties of nucleotide phosphohydrolase of aspergillus niger

An enzyme that catalyzes the hydrolysis of orthophosphate from the pyrimidine ribonucleotide cytidine monophosphate optimally at pH 3.5-4 was partially purified from mycelial extracts of A. niger. The enzyme is an acid phosphatase catalysing the phosphohydrolysis of phenylphosphate at almost the same rate as cytidilic acid. The enzyme appears to exist in two forms [isoenzymes] which can be separated on TEAE-cellulose column. Some properties of both isoenzymes e.g. PH temperature activities relationships, substrate specificity, thermal stability and metal requirements were studied

Allantoate degradation by some filamentous fungi

Allantoate degradation by cell-free extracts of some selected fungi, proved to utilize uric acid as solo source of nitrogen, was studied. Three patterns for allantoate catabolism, by extracts of the tested fungi were demonstrated: A] Formation of both ureidoglycolate and glyoxylate form allantoate. B] Formation of glyoxylate from allantoate. C] Formation of ureidoglycolate form allantoate. Extracts of fungal organisms of the second group [B] catalyzed the hydrolysis of allantoate to ureidoglycolate, but the rate of degradation of the latter, was faster that that of its formation. With regard to the third group [C], it has been confirmed that glyoxylate was transformed rapidly to other product[s]. Therefore, it could not be detected as a degradation product from allantoate