Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.10.3.1 (tyrosinase)
 9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lactate production and oxygen consumption were studied in single cell suspension prepared from solid tumours of the black-melanotic (Ma), brown-melanotic (MI) and amelanotic (Ab) melanomas of hamster. Aerobic lactase production was about 5 times higher in the fast growing Ab melanoma than in the slow growing Ma and MI melanomas. Aerobic lactate production in both melanotic hamster melanomas was stimulated by 3-(3,4-dihydroxyphenyl)-L-alanine. This compound was without effect on the cells isolated from amelanotic hamster melanoma. L-Phenylalanine, a known competitive tyrosinase inhibitor reduced the stimulatory effect of L-DOPA on the the lactate production. Oxygen consumption was similar in all three melanomas. The oxygen consumption was inhibited completely by 1 mM potassium cyanide in the Ab melanoma but only in about 1/3 in the Ma and MI melanomas. The Pasteur effect was higher in relative terms and lower in absolute terms in the melanotic melanomas than in the Ab melanoma only . The Crabtree effect was present in the Ab melanoma only. Thus glycolysis measured by aerobic and anaerobic lactic acid formation, and cell respiration, measured by oxygen consumption sensitive to KCN, were both higher in the more malignant, less differentiated Ab melanoma than in the Ma and MI melanomas. The suggestion is presented that the process of melanogenesis influences both aerobic glycolysis and the KCN insensitive consumption in the melanotic hamster melanomas.
 ...
PMID:Biochemical characterization of three hamster melanoma variants--II. Glycolysis and oxygen consumption. 669 97

Hydroquinone galactoside (HQ-Gal) as a potential skin whitening agent was synthesized by the reaction of lactase (beta-galactosidase) from Kluyveromyces lactis, Aspergillus oryzae, Bacillus circulans, and Thermus sp. with lactose as a donor and HQ as an acceptor. Among these lactases, the acceptor reaction involving HQ and lactose with K. lactis lactase showed a higher conversion ratio to HQ-Gal (60.27%). HQ-Gal was purified using butanol partitioning and silica gel column chromatography. The structure of the purified HQ-Gal was determined by nuclear magnetic resonance, and the ionic product was observed at m/z 295 (C12H16O7Na)+ using matrix assisted laser desorption ionization time-of-flight mass spectrometry. HQ-Gal was identified as 4-hydroxyphenyl-beta-d-galactopyranoside. The optimum conditions for HQ-Gal synthesis by K. lactis determined using response surface methodology were 50 mM HQ, 60 mM lactose, and 20 U mL(-1) lactase. These conditions produced a yield of 2.01 g L(-1) HQ-Gal. The half maximal inhibitory concentration (IC50) of diphenylpicrylhydrazyl scavenging activity was 3.31 mM, indicating a similar antioxidant activity compared to beta-arbutin (IC50=3.95 mM). The Ki value of HQ-Gal (0.75 mM) against tyrosinase was smaller than that of beta-arbutin (Ki=1.97 mM), indicating its superiority as an inhibitor. HQ-Gal inhibited (23%) melanin synthesis without being significantly toxic to the cells, while beta-arbutin exhibited only 8% reduction of melanin synthesis in B16 melanoma cells compared with the control. These results indicate that HQ-Gal may be a suitable functional component in the cosmetics industry.
 ...
PMID:Enzymatic synthesis and characterization of hydroquinone galactoside using Kluyveromyces lactis lactase. 2068 52