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Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616
4To whom correspondence and reprint requests should be addressed.
The objective of this study was to determine the effect of dietary
protein and taurine on cysteine desulfhydration in various kitten
tissues. Cysteine desulfhydration was assessed in liver, kidney,
skeletal muscle, heart, spleen, brain and jejunum of kittens fed one of
the following diets for 5 wk: 20% protein, 0% taurine diet (LP0T);
20% protein, 0.15% taurine diet (LPNT); 60% protein, 0% taurine
diet (HP0T); and 60% protein, 0.15% taurine diet (HPNT). Cats fed
LP0T and HP0T had been fed a taurine-free diet for 10 wk before the
5-wk experiment. The activity of cysteine desulfhydration was
determined by measuring the production of H235S
from 35S-cysteine in the presence and absence of
-ketoglutarate (
KG) in the incubation medium. Liver and kidney
had the highest total activities among the tissues tested
(P < 0.01). Total hepatic desulfhydration
activities [µmol H2S/(min · kg body
wt)] in cats fed LP0T, LPNT, HP0T and HPNT were (mean ± SEM) 117 ± 6, 135 ± 10, 137 ± 10 and 190
± 9, respectively. Dietary taurine had a significant
effect on activity when expressed per gram liver (P
< 0.01), per gram protein (P < 0.05) and per
kilogram body weight (P < 0.001). Dietary protein
had a significant effect (P < 0.001) only when
activity was expressed relative to body weight because of the
significant effect of protein on relative liver weight. The direct
pathway via cysteine desulfhydrase appears to be the major route of
cysteine desulfhydration in kitten liver because the values obtained in
the absence of
KG were 8188% of those obtained in the presence of
KG.
KEY WORDS: cysteine desulfhydration cysteine desulfhydrase kittens dietary protein dietary taurine
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