Dl. Bella et Mh. Stipanuk, EFFECTS OF PROTEIN, METHIONINE, OR CHLORIDE ON ACID-BASE-BALANCE AND ON CYSTEINE CATABOLISM, American journal of physiology: endocrinology and metabolism, 32(5), 1995, pp. 910-917
Metabolism of cysteine to sulfate results in production of H+, whereas
metabolism of cysteine to taurine does not. Rats were fed a basal low
-protein dieter a diet with excess protein, methionine, or chloride fo
r 2-3 wk, and effects of these treatments on acid-base homeostasis and
on cysteine metabolism were determined. Hepatocytes from rats fed die
ts with excess methionine, but not from rats fed diets with excess pro
tein or chloride, catabolized a high proportion of cysteine to taurine
(32% vs. 4-7% for other groups), and intact rats fed excess methionin
e excreted more sulfur as taurine (51% of total sulfur vs. 1-6% for ot
her groups). The formation of taurine vs. sulfate as the end product o
f cysteine catabolism provides a metabolic compensation that minimizes
the acid load in rats fed excess sulfur amino acids. However, increas
ed production of taurine vs. sulfate is not a general adaptive respons
e to acidogenic diets.