Studies on aromatic amino acid oxidase activity in ram spermatozoa: role of pyruvate as an antioxidant

Over the years, accumulating evidence has indicated that D-serine represents the main endogenous ligand of NMDA (N-methyl-D-aspartate) receptors. In the brain, the concentration of D-serine stored in cells is defined by the activity of two enzymes: serine racemase (responsible for both the synthesis and degradation) and D-amino acid oxidase (which catalyses D-serine degradation). The present review is focused on human D-amino acid oxidase, discussing the mechanisms involved in modulating enzyme activity and stability, with the aim to substantiate the pivotal role of D-amino acid oxidase in brain D-serine metabolism.

Download Full-text

Role of Castration and Androgens in D-Amino Acid Oxidase Activity of Tissues

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1956.185.2.250 ◽

1956 ◽

Vol 185 (2) ◽

pp. 250-256 ◽

Cited By ~ 12

Author(s):

Barbara R. Endahl ◽

Charles D. Kochakian

Keyword(s):

Enzyme Activity ◽

Amino Acid ◽

Guinea Pig ◽

Oxidase Activity ◽

The Other ◽

Maximum Effect ◽

Acid Oxidase ◽

Amino Acid Oxidase ◽

Small Doses

A large number of C19 steroids were able to markedly increase the d-amino acid oxidase activity of the kidney of the castrated mouse. The maximum effect was attained within 21 days of treatment and with relatively small doses of the most potent androgens. On the other hand, neither castration nor various androgens were able to significantly alter the d-amino acid oxidase activity of either the kidney or liver of the castrated rat and guinea pig. Furthermore, age did not influence the enzyme activity of the tissues of the rat (2–8 months of age) or the guinea pig (4–8 months of age). Estradiol produced a small increase in the d-amino acid oxidase activity of the kidney of the mouse but estrone, methoxybisdehydrodiosynolic acid and several corticoids were ineffective.

Download Full-text

Impairment of Platelet Aggregation by Echis colorata Venom Mediated by L-Amino Acid Oxidase or H2O2

Thrombosis and Haemostasis ◽

10.1055/s-0038-1657280 ◽

1982 ◽

Vol 48 (03) ◽

pp. 277-282 ◽

Cited By ~ 22

Author(s):

I Nathan ◽

A Dvilansky ◽

T Yirmiyahu ◽

M Aharon ◽

A Livne

Keyword(s):

Hydrogen Peroxide ◽

Amino Acid ◽

Platelet Aggregation ◽

Snake Venom ◽

Oxidase Activity ◽

Enzyme Preparation ◽

Acid Oxidase ◽

Crude Venom ◽

Amino Acid Oxidase ◽

Hemostatic Disorders

SummaryEchis colorata bites cause impairment of platelet aggregation and hemostatic disorders. The mechanism by which the snake venom inhibits platelet aggregation was studied. Upon fractionation, aggregation impairment activity and L-amino acid oxidase activity were similarly separated from the crude venom, unlike other venom enzymes. Preparations of L-amino acid oxidase from E.colorata and from Crotalus adamanteus replaced effectively the crude E.colorata venom in impairment of platelet aggregation. Furthermore, different treatments known to inhibit L-amino acid oxidase reduced in parallel the oxidase activity and the impairment potency of both the venom and the enzyme preparation. H2O2 mimicked characteristically the impairment effects of L-amino acid oxidase and the venom. Catalase completely abolished the impairment effects of the enzyme and the venom. It is concluded that hydrogen peroxide formed by the venom L-amino acid oxidase plays a role in affecting platelet aggregation and thus could contribute to the extended bleeding typical to persons bitten by E.colorata.

Download Full-text