Acyl-CoA: monoglyceride acyltransferase (MGAT; EC 2.3.1.22) has been studied in human small intestinal mucosa by means of a spectrophotometric method based on the detection of liberated CoA employing 5,5´-dithiobis-(2-nitrobenzoic acid). With optimal assay conditions available the pH optimum was spread between 7.0 and 7.7 with a maximum at a pH of 7.4. Dependent on its concentration one of the substrates, palmitoyl-CoA, caused severe inhibition which was largely prevented by the addition of albumin. Using palmitoyl-CoA and 1 -monooleoylglycerol as substrates specific activities were 23.0 ± 8.4 in total homogenates compared with 92.9 ± 28.3 nmol CoA released/min/mg protein in microsomal fractions from jejunal mucosa. Concerning the substrate specificity, a broad acyl-donor pattern exists with maximal activities for C_10:0 to C_16:0, the highest for C_16:0. A preferential esterification of acyl-acceptors was shown for 2-monoacylglycerols as compared with the 1 -isomers, and for monoacylglycerols with unsaturated versus saturated fatty acids. MGAT was mainly localized in the microsomal fraction. The properties of MGAT from human small intestine are discussed with respect to the intestinal enzyme from other species.

Severe potassium deficiency is an uncommon cause of rhabdomyolysis. We recently treated a 45-year-old patient with myalgia, serious generalized weakness, increased serum creatine kinase and myoglobin level as well as excessive hypokalemia. Histological examination of deltoid muscle biopsy showed rhabdomyolysis. After complete recovery of muscle damage by potassium substitution Bartter's syndrome proved to be the cause of initial and persistent hypokalemia.

The uptake and metabolism of long chain fatty acids in isolated mucosal cells from chicken small intestine are studied. The viability of the isolated enterocytes is proven by linear oxygen consumption, C0₂ and lactate formation from glucose and the active transport of glucose. The transport of palmitic and oleic acid is mediated by passive diffusion. This is demonstrated by the following results: (1) no saturation kinetics in the concentration range of 0.1 -10.0 mM; (2) no competitive inhibition of the uptake by structurally related compounds; (3) no influence of 2,4-DNP and cyanide of the uptake; (4) the uptake is independent of sodium ions. Uptake rates of palmitic and oleic acid from suspensions are significantly higher than from the corresponding fatty acid-bovine serum albumin complexes. In both cases the uptake of palmitic acid proceeds faster than the uptake of oleic acid. Palmitic acid is oxidized to C0₂ and incorporated into glycerides by enterocytes. Glucose serves as a glyceride-glycerol precursor. Its addition decreases the oxidation of the fatty acids and enhances glyceride synthesis markedly. Free glycerol is phosphorylated by enterocytes and can also serve as a glyceride-glycerol precursor.

In a 35-year-old man with the full picture of Fabry's disease there was an almost fourfold increase of trihexosylceramide concentration in plasma and a decrease in the alpha-galactosidase activity to 13 percent as compared with the values from a control group. Using the same biochemical methods it could be shown that two nephews of the patient are hemizygote carriers and that two sisters and the mother of the patient are heterozygote carriers. Causative treatment of the disease is unknown. In this patient the attacks of pain could be permanently improved with phenytoin and carbamazepin.

Die biologische Bedeutung des Zinks für den Säugetier-Organismus erkannten Todd und Mitarbeiter (54), die