The first sequenced normal hemoglobin lacking histidine in position 146 of the beta-chains. The primary structures of the major and minor hemoglobin components of the great crested newt (Triturus cristatus, Urodela, Amphibia)

The hemoglobin of the Great Crested Newt (Triturus cristatus), an animal maintaining the gas exchange to about 85% through the skin, consists of a major (HbM = 65%) and a minor (Hbm = 35%) component. The primary structures of the four chains are presented. They could be separated by reversed-phase HPLC and were cleaved with trypsin and additionally by acid hydrolysis. Both the native chains and their peptides were sequenced by liquid and gas phase sequenators. At the N-terminus the alpha M-chains are by one amino-acid residue longer and the beta M-chains by one residue shorter, resulting in a chain length of 142 and 145, respectively. The alpha m-chains are of normal length whereas in the beta m-chains the C-terminal histidine in position 146 is missing. Both alpha-chains differ by 50 residues (35.2%) and the beta-chains by 63 (43.2%). The alpha-chains were compared with those of other salamandroid hemoglobins. The difference to human hemoglobin is marked by 61 (43.3%) amino-acid substitutions in both alpha-chains and by 78 (53.4%) in both beta-chains. Numerous heme contacts and positions involved in the subunit interface are affected by replacements. The most interesting of them were studied by molecular modeling. The importance of the missing beta m-146(HC3)His and of the substitution of several amino-acid residues involved in the binding of organic phosphates is discussed with respect to the reduced Bohr effect of Triturus cristatus hemoglobin.     

The thiol proteinases from the latex of Carica papaya L. II. The primary structure of proteinase omega

The complete primary structure of the proteinase omega isolated from the latex of the Carica papaya fruits is given. The polypeptide chain contains 216 amino-acid residues, the alignment of which was deduced from sequence analyses of the native enzyme, the tryptic, chymotryptic, peptic and thermolysinolytic peptides and facilitated due to the considerable degree of homology with papain and actinidin. The location of the three disulfide bridges could be established with the help of peptic and thermolysinolytic fragments. Proteinase omega shares 148 identical amino-acid residues (68.5%) with papain and 108 ones (50%) with actinidin, including the three disulfide bridges and the free cysteine residue required for activity, as well as most of the other amino-acid residues involved in the catalytic mechanism and two thirds of the glycine residues which are of structural significance. The homology with other cysteine proteinases of different origin is discussed.     

Spin-label electron spin resonance studies on the interactions of lysine peptides with phospholipid membranes.

The interactions of lysine oligopeptides with dimyristoyl phosphatidylglycerol (DMPG) bilayer membranes were studied using spin-labeled lipids and electron spin resonance spectroscopy. Tetralysine and pentalysine were chosen as models for the basic amino acid clusters found in a variety of cytoplasmic membrane-associating proteins, and polylysine was chosen as representative of highly basic peripherally bound proteins. A greater motional restriction of the lipid chains was found with increasing length of the peptide, while the saturation ratio of lipids per peptide was lower for the shorter peptides. In DMPG and dimyristoylphosphatidylserine host membranes, the perturbation of the lipid chain mobility by polylysine was greater for negatively charged spin-labeled lipids than for zwitterionic lipids, but for the shorter lysine peptides these differences were smaller. In mixed bilayers composed of DMPG and dimyristoylphosphatidylcholine, little difference was found in selectivity between spin-labeled phospholipid species on binding pentalysine. Surface binding of the basic lysine peptides strongly reduced the interfacial pK of spin-labeled fatty acid incorporated into the DMPG bilayers, to a greater extent for polylysine than for tetralysine or pentalysine at saturation. The results are consistent with a predominantly electrostatic interaction with the shorter lysine peptides, but with a closer surface association with the longer polylysine peptide.     

Nucleosome assembly in vitro: separate histone transfer and synergistic interaction of native histone complexes purified from nuclei of Xenopus laevis oocytes.

High speed supernatants of Xenopus laevis oocyte nuclei efficiently assemble DNA into nucleosomes in vitro under physiological salt conditions. The assembly activity cofractionates with two histone complexes composed of the acidic protein N1/N2 in complex with histones H3 and H4, and nucleoplasmin in complex with histones H2B and H2A. Both histone complexes have been purified and their nucleosome assembly activities have been analysed separately and in combination. While the histones from the N1/N2 complexes are efficiently transferred to DNA and induce supercoils into relaxed circular plasmid DNA, the nucleoplasmin complexes show no supercoil induction, but can also transfer their histones to DNA. In combination, the complexes act synergistically in supercoil induction thereby increasing the velocity and the number of supercoils induced. Electron microscopic analysis of the reaction products shows fully packaged nucleoprotein structures with the typical nucleosomal appearance resulting in a compaction ratio of 2.8 under low ionic strength conditions. The high mobility group protein HMG-1, which is also present in the soluble nuclear homogenate from X. laevis oocytes, is not required for nucleosome core assembly. Fractionation experiments show that the synergistic effect in the supercoiling reaction can be exerted by histones H3 and H4 bound to DNA and the nucleoplasmin complexes alone. This indicates that it is not the synchronous action of both complexes which is required for nucleosome assembly, but that their cooperative action can be resolved into two steps: deposition of H3 and H4 from the N1/N2 complexes onto the DNA and completion of nucleosome core formation by addition of H2B and H2A from the nucleoplasmin complexes.     

Effect of Growth Temperature on the Lipid Composition of Cyanidium caldarium: II. Glycolipid and Phospholipid Components

Cyanidium caldarium was grown at 20 and 55 C and harvested during exponential growth phase. Lipids were extracted and separated by silicic acid column and thin layer chromatography. The major glycolipids were identified as mono- and digalactosyl diglyceride and sulfolipid. Major phospholipids were identified as phosphatidyl choline and phosphatidyl ethanolamine. The cells grown at 20 C contained significantly larger quantities of these glycolipids and phospholipids than cells grown at 55 C.     

Effect of Growth Temperature on the Lipid Composition of Cyanidium caldarium: I. Class Separation of Lipids

Cyanidium caldarium was cultured at 20 and 55 C and harvested during exponential growth phase. Comparative lipid studies on each cell type show a decrease by one-half of the total lipid in cells grown at 55 C over cells grown at 20 C. While the distribution of lipid into each of five lipid classes was not influenced by high temperature (55 C), the degree of unsaturation was greatly affected. Ratios of unsaturated to saturated fatty acids in these cells decreased 3-fold with increased temperature in the growth environment. Cells cultured at 20 C contained 30% of their fatty acids as linolenic while this fatty acid could not be detected in cells cultured at 55 C.     

Electron microscopic studies of proteoglycan aggregates from bovine articular cartilage.

Proteoglycan aggregates from bovine articular cartilage have been visualized by electron microscopy of mixed proteoglycan-cytochrome c monolayers. The proteoglycan aggregates consist of proteoglycan subunits arising laterally at fairly regular intervals (20 to 30 nm) from the opposite sides of an elongated filamentous structure. The filamentous backbone in individual aggregates varies in length from 400 to 4000 nm. The individual proteoglycan subunits in the aggregate vary in length from 100 to 400 nm. However, there is no difference in the average size of the proteoglycan subunits associated with the largest or smallest aggregates. The sizes of the individual aggregates are determined mainly by the lengths of their filamentous backbones. The stoichiometry of binding of subunits to filament, calculated from the data reported here, is close to that for the binding of subunits to hyaluronic acid reported by others.