Functional characterization of constituent enzyme fractions of mycobacillin synthetase.

The enzyme fraction A, a constituent enzyme of the three-fraction enzyme mycobacillin synthetase, independently and sequentially activated five amino acids starting from L-proline, producing the pentapeptide Pro(Asp1,Glu1,Tyr1)Asp. The fractions B and C were unable to function independently. However, the fraction B synthesized the nonapeptide Pro(Asp3,Glu1,Tyr2,Ser1)Leu, sequentially activating the pentapeptide and next four amino acids, whereas the fraction C synthesized mycobacillin by the sequential activation of the nonapeptide and the remaining four amino acids. The pH optima of the above enzymes are almost identical (pH 7.8), but their Km values are a little different.     

Echitoserpidine: A new alkaloid of the fruits of Alstonia venenata

The structure of echitoserpidine, a new alkaloid of the fruits of Alstonia venenata has been established as (1) on the basis of spectral and chemical evidence.     

Inositol is the water-soluble product of acetylcholine-stimulated breakdown of phosphatidylinositol in mouse pancreas.

The water-soluble products of acetylcholine-stimulated breakdown of phosphatidylinositol in mouse pancreas were analyzed by two different and independent procedures. There was an increased formation of free inositol throughout the period of phosphatidylinositol breakdown; no evidence was obtained for acetylcholine-stimulated formation of either inositol 1,2-cyclic phosphate or inositol 1-phosphate under any of the conditions used. The observations suggest that the acetylcholine-stimulated reaction is phosphatidylinositol → phosphatidic acid + inositol. This might occur by either phospholipase D activity, or through complete or partial reversal of the cytidine nucleotide pathway of phosphatidylinositol biosynthesis.     

Genetic load in an isolated tribal population of south India

Summary The Kota of Nilgiri Hills, Tamilnadu, are an isolated tribal population and occupy the lowest stratum in the local social hierarchy. They have developed an economic symbiotic relationship with other tribes of the Nilgiri Hills (e.g., Toda, Kurumba, Badaga), but have almost no social relationship with other communities, such as the Hindu and Muslim, communities, etc. The total population of the Kota is about 1200. Consanguineous marriages are highly favoured in this group.This paper presents data on prenatal, infant and adolescent mortality in relation to the degree of inbreeding. No perceptible difference has been found in mortality figures between consanguineous and non-consanguineous marriages. This may be due to the long history of inbreeding among the Kota. No case of visible congenital malformation has been noticed.The estimates of genetic load as revealed by inbreeding data indicate that genetic load in the Kota is low (perhaps about 1 lethal equivalent per gamete); it is also low in comparison with that in other Indian populations.     

Phosphatidyl inositol inhibition of a sperm cyclic AMP-independent protein kinase

Phosphatidyl inositol has been found to inhibit strongly the activity of a cyclic AMP-independent protein kinase located on the external surface of goat epididymal intact spermatozoa. Phosphatidyl inositol at a concentration as low as 10 micrograms/ml inhibited nearly 50% of the ecto-kinase activity for the phosphorylation of the exogenous protein substrate: casein. Phosphatidyl ethanolamine at a relatively high concentration (125 micrograms/ml) inhibited slightly (approx 25%) the activity of the enzyme whereas other phospholipids: phosphatidyl serine and choline, diacyl glycerol, phosphatidic acid and myo-inositol-2-phosphate had no appreciable effect on the kinase activity. Phosphatidyl inositol has also served as a potent inhibitor of the phosphorylation of sperm ecto-phosphoproteins by the endogenous kinase activity of intact spermatozoa. By thin layer chromatography it has been shown that the observed inhibitory effect of the phospholipid was not due to any impurities or degraded products of phosphatidyl inositol. Phosphatidyl inositol inhibited the kinase activity noncompetitively with respect to casein and Mg2+ but uncompetitively with respect to ATP. The results raised the possibility that phosphatidyl inositol-mediated high affinity inhibition of protein kinase(s), may constitute a novel mechanism for the regulatory actins of the phospholipid in mammalian cells.