Sheu S Y, Lin Y C, Chiang H C
School of Pharmacy, Taipei Medical College, Taiwan, R.O.C.
Anticancer Res. 1996 Nov-Dec;16(6B):3571-6.
Fourteen cytokinins were tested for their inhibitory effects on xanthine oxidase. The enzyme, xanthine oxidase catalyses the oxidation of hypoxanthine to xanthine and of xanthine to uric acid which has lambda max of 295 nm, forming the basis for a spectrophotometric assay of the activity of xanthine oxidase. The results showed that adenine-HCl, N6-(2-isopentenyl)-adenine, purine and DL-dihydrozeatin displayed very potent activities (IC50 = 1.92, 10.99, 60.98 and 86.36 microM respectively). Their apparent inhibition constants (Ki) were 2.20, 17.99, 13.59 and 115.62 microM, and induced competitive, uncompetitive, competitive and non-competitive type inhibitions respectively with respect to the substrate xanthine.
测试了十四种细胞分裂素对黄嘌呤氧化酶的抑制作用。黄嘌呤氧化酶催化次黄嘌呤氧化为黄嘌呤以及黄嘌呤氧化为尿酸，尿酸的最大吸收波长为295nm，这构成了分光光度法测定黄嘌呤氧化酶活性的基础。结果表明，盐酸腺嘌呤、N6-(2-异戊烯基)腺嘌呤、嘌呤和DL-二氢玉米素表现出很强的活性（IC50分别为1.92、10.99、60.98和86.36微摩尔）。它们的表观抑制常数（Ki）分别为2.20、17.99、13.59和115.62微摩尔，并且分别对底物黄嘌呤诱导竞争性、非竞争性、竞争性和非竞争性抑制。
