Pacifici G M, Franchi M, Giuliani L
Department of General Pathology, Medical School, University of Pisa, Italy.
Pharmacology. 1989;38(3):146-50. doi: 10.1159/000138531.
The kinetics of sulphotransferase (ST) were studied at varying concentrations of 2-naphthol or adenosine 3'-phosphate-5'-phosphosulphate (PAPS) in specimens of ileum and colon mucosa obtained from 6 subjects. When 2-naphthol was the variable substrate the enzyme obeyed non-Michaelis-Menten kinetics. The enzyme kinetic profile consists of two phases: one at higher and the other at lower activity for 2-naphthol. The maximum velocity of reaction (Vmax, mean +/- SD; pmol/min.mg protein) of the high-affinity phase was 403 +/- 82 (ileum) and 216 +/- 42 (colon) (p less than 0.01). Vmax for the low-affinity phase was 669 +/- 105 (ileum) and 415 +/- 84 (colon) (p less than 0.01). Km (mean +/- SD) of the high affinity phase was 0.034 +/- 0.004 (ileum) and 0.025 +/- 0.001 mmol/l (colon) (NS) and that of the low-affinity phase was 0.101 +/- 0.013 (ileum) and 0.095 +/- 0.014 mmol/l (colon) (NS). At varying concentrations of PAPS the enzyme obeyed Michaelis-Menten kinetics. Vmax (mean +/- SD) was 995 +/- 163 (ileum) and 520 +/- 114 (colon) pmol/min.mg protein (p less than 0.02). Km was 0.096 +/- 0.008 (ileum) and 0.079 +/- 0.012 mmol/l (colon) (NS). The ST of ileum differs from that of colon for Vmax only.
在取自6名受试者的回肠和结肠黏膜标本中，研究了不同浓度的2 - 萘酚或3'-磷酸 - 5'-磷酸腺苷硫酸酯（PAPS）条件下的磺基转移酶（ST）动力学。当2 - 萘酚作为可变底物时，该酶遵循非米氏动力学。酶动力学曲线由两个阶段组成：一个是2 - 萘酚活性较高的阶段，另一个是活性较低的阶段。高亲和力阶段的最大反应速度（Vmax，平均值±标准差；pmol/分钟·毫克蛋白）在回肠中为403±82，在结肠中为216±42（p＜0.01）。低亲和力阶段的Vmax在回肠中为669±105，在结肠中为415±84（p＜0.01）。高亲和力阶段的Km（平均值±标准差）在回肠中为0.034±0.004，在结肠中为0.025±0.001 mmol/升（无显著性差异），低亲和力阶段的Km在回肠中为0.101±0.013，在结肠中为0.095±0.014 mmol/升（无显著性差异）。在不同浓度的PAPS条件下，该酶遵循米氏动力学。Vmax（平均值±标准差）在回肠中为995±163，在结肠中为520±114 pmol/分钟·毫克蛋白（p＜0.02）。Km在回肠中为0.096±0.008，在结肠中为0.079±0.012 mmol/升（无显著性差异）。回肠的ST与结肠的ST仅在Vmax方面存在差异。
