Heme binding and polymerization by Plasmodium falciparum histidine rich protein II: influence of pH on activity and conformation.

The histidine rich protein II (HRPII) from Plasmodium falciparum has been implicated as a heme polymerase which detoxifies free heme by its polymerization to inactive hemozoin. Histidine-iron center coordination is the dominant mechanism of interaction between the amino acid and heme. The protein also contains aspartate allowing for ionic/coordination interactions between the carboxylate side chain and the heme metal center. The pH profile of heme binding and polymerization shows the possibility of these two types of binding sites being differentiated by pH. Circular dichroism studies of the protein show that pH and heme binding cause a change in conformation above pH 6 implying the involvement of His-His+ transitions. Heme binding at pHs above 6 perturbs HRPII conformation, causing an increase in helicity.     

Purification of four gelatin-binding proteins from bovine seminal plasma by affinity chromatography

Bovine seminal plasma contains three similar acidic proteins, which we have previously designated as BSP-A1, BSP-A2, and BSP-A3. These proteins contain two homologous domains that are similar to type II structures present in the gelatin-binding domain of fibronectin. The present data have revealed that these proteins, like fibronectin, also form complexes with gelatin, a denatured collagen. Based on this property, a single step affinity purification method has been developed. In addition to these three proteins BSP-A1, -A2 and -A3, another protein with an apparent molecular weight of 30,000 dalton (named BSP-30-kDa) also bound to the gelatin-agarose column. Elution of these proteins from affinity columns using a linear gradient of either urea or arginine gave essentially the same pattern with a high yield of 90–95%. The purified proteins were homogeneous by SDS-polyacrylamide gel electrophoresis, amino acid composition and HPLC. Chromatography of bull seminal vesicular fluid also exhibited an elution pattern similar to that obtained for bull seminal plasma. The availability of these purified proteins should aid in understanding the physiology of these gelatin-binding proteins.     

Structural organization of cholera toxin gene and its expression in an environmental non-pathogenic strain ofVibrio cholerae

Non-pathogenic, environmental strain ofVibrio cholerae, ELTOR Ogawa EW6 carries a copy of the cholera toxin gene in its chromosome. Restriction enzyme digestion followed by Southern blot analysis revealed that the structure of the cholera toxin gene in this organism is different from that found in the virulent strains. The xbaI site which has been found to be conserved in the cholera toxin of the virulent strains examined so far, is absent here. Results of the RNA dot blot analysis indicated that the cholera toxin gene in EW6 is transcribed much less efficiently compared to the cholera toxin gene present in the virulent strainVibrio cholerae classical Inaba 569B.     

Resolution of genetic and uterine environmental effects in a family study of new dermatoglyphic measure: sole pattern ridge counts

The heritability of sole pattern ridge counts was examined in two family studies of endogamous castes from peninsular India. The phenotypes included ridge counts for each of the eight configurational areas separately, all areas combined, and only distal areas combined. Differences in heritability estimates were found between populations as well as among the individual configurational areas. Although some ridge counts do not show familial resemblance, others appear to be moderately heritable. Estimates of h2 range from 0.36 to 0.63 in one family series and from 0.22 to 0.51 in the other. In addition, significant uterine environmental effects were detected in one family series but not in the other.     

Fatty acyl-coenzyme A is required for budding of transport vesicles from Golgi cisternae

We describe a new role for fatty acylation. Conditions were established under which vesicular transport from the cis to the medial Golgi compartment in vitro depends strongly upon the addition of a fatty acyl-coenzyme A, e.g., palmitoyl-CoA. Using an inhibitor of long-chain acyl-CoA synthetase, we demonstrate that the fatty acid has to be activated by CoA to stimulate transport. A nonhydrolyzable analog of palmitoyl-CoA competitively inhibits transport. Electron microscopy and biochemical studies show that fatty acyl-CoA is required for budding of (non-clathrin-) coated transport vesicles from Golgi cisternae and that budding is inhibited by the nonhydrolyzable analog.     

Conformations of peptides containing Z-alpha,beta-dehydroleucine (delta ZLeu). A comparison of Boc-Pro-delta ZLeu-Gly-NHEt and Boc-Pro-delta ZPhe-Gly-NHEt

Two tripeptides of the type Boc-Pro-delta ZX-Gly-NHEt (where X = Leu, Phe) have been synthesized and their solution conformations investigated by 270 MHz 1H n.m.r. and i.r. spectroscopy. These conformational studies indicated that delta ZLeu, similar to delta ZPhe, has a strong tendency to stabilize folded Type II beta-turn conformations when present at i + 2 position.     

Noncovalent modulation by ATP of the acyl transfer from acyl-glyceraldehyde-3-phosphate dehydrogenase to phosphate

The effect of ATP on the formation, spectral properties, and reactions of [beta-(2-furyl)acryloyl]glyceraldehyde-3-phosphate dehydrogenase (FA-GPDH) has been investigated. The chromophoric FA-GPDH has the advantage of providing spectrophotometric signals of the interaction of acyl enzyme with nucleotides and dinucleotides. The results are consistent with the exclusive existence of two acyl-enzyme conformations previously inferred from the interaction of the acyl enzyme with NAD+ and NADH. ATP interaction stabilizes a conformation different from that stabilized by NAD+. The inhibitory effects of ATP on these reactions are consistent with the reported inhibitory effect of ATP on the steady-state reaction with the true substrate. The physiological significance of these results to the regulation of glycolysis, via the ligand-dependent fate of 3-phosphoglycerol-GPDH, is discussed.