Glazenburg E J, Jekel-Halsema I M, Scholtens E, Baars A J, Mulder G J
J Nutr. 1983 Jul;113(7):1363-73. doi: 10.1093/jn/113.7.1363.
Amounts of the sulfur-containing amino acids methionine and cysteine in synthetic diets were decreased from 22.8 mmol methionine (= 100 Met) and 26.4 mmol cysteine (= 100 Cys) per kilogram diet in the control group to (Met/Cys) 100:0, 75:0, 50:0, 25:0 and 25:25, respectively, in experimental diet groups, in order to evaluate effects of limiting sulfur supply on the availability of cosubstrates for conjugation. Below a Met level of 22.8 mmol/kg growth rates decreased. Urinary excretion of inorganic sulfate decreased to 10-20% of control values in all groups. Feeding diets 100:0 and 75:0 for 14 days resulted in a decrease of the concentration of inorganic sulfate in serum; on diets 25:25 and 25:0 an increase was found. A decreased content of methionine/cysteine resulted in an increase in cystine, a decrease in taurine and no change in methionine concentration in serum. In all experimental groups the glutathione concentration in the liver diminished to about 20% of control values, and the hepatic concentration of "active sulfate" (PAPS: adenosine 3'-phosphate 5'-phosphosulfate) decreased in most rats. At the lowest methionine supply, sulfate conjugation of acetaminophen decreased to 50% of control. The formation of the acetaminophen glutathione conjugate remained unaffected, in spite of a decreased hepatic glutathione availability.
为了评估限制硫供应对共底物结合可用性的影响，合成日粮中含硫氨基酸甲硫氨酸和半胱氨酸的含量从对照组每千克日粮22.8毫摩尔甲硫氨酸（=100%甲硫氨酸）和26.4毫摩尔半胱氨酸（=100%半胱氨酸）分别降至实验日粮组的（甲硫氨酸/半胱氨酸）100:0、75:0、50:0、25:0和25:25。当甲硫氨酸水平低于22.8毫摩尔/千克时，生长速率下降。所有组无机硫酸盐的尿排泄量降至对照值的10 - 20%。饲喂100:0和75:0日粮14天导致血清中无机硫酸盐浓度降低；而饲喂25:25和25:0日粮时则发现浓度升高。甲硫氨酸/半胱氨酸含量降低导致血清中胱氨酸增加、牛磺酸减少且甲硫氨酸浓度无变化。在所有实验组中，肝脏中的谷胱甘肽浓度降至对照值的约20%，并且大多数大鼠肝脏中“活性硫酸盐”（PAPS：3'-磷酸腺苷5'-磷酸硫酸）的浓度降低。在最低甲硫氨酸供应水平下，对乙酰氨基酚的硫酸盐结合降至对照的50%。尽管肝脏中谷胱甘肽可用性降低，但对乙酰氨基酚谷胱甘肽结合物的形成仍未受影响。
