Biomedical subjects
A Rich
Publications and source records attributed to A Rich.
A crystallographic investigation of citrate synthase from pig and chicken heart muscle.
Explore the source record for details and available documents.
Myogenesis in primary cell cultures from Drosophila melanogaster: protein synthesis and actin heterogeneity during development.
Muscle cell cultures from Drosophila melanogaster were obtained by plating dissociated gastrula stage embryo cells on protamine-treated culture dishes. They myogenic cells in these cultures fuse to form multinucleated pulsating cells by 15 hr after plating. An analysis of protein synthesis during myogenesis in these cultures, as measured by the incorporation of 35S-methionine and analyzed by two-dimensional polyacrylamide gel electrophoresis, showed profound changes in the pattern of protein synthesis. This analysis enabled us to identify three distinct classes of proteins. Class A proteins, the most abundant, are synthesized continuously throughout myogenesis, class B proteins are those proteins whose synthesis is initiated during myogenesis and continued throughout development; class C proteins are those synthesized at specific times during development. In addition, three forms of actin have been identified in these cultures. Actin I, which shows increased synthesis concomitant with the myogenic development in these cultures, is apparently a muscle-specific form of actin. Actin II, the predominant "cytoplasmic" form of actin in the nonmuscle Schneider cell line 2, is also the major form in the gastrula cultures before differentiation begins. Synthesis of this actin continues in the myogenic cultures. Actin III is a rapidly turning over form of actin which does not accumulate in either the Schneider cells or the myogenic cultures.
The three-dimensional structure of transfer RNA.
Explore the source record for details and available documents.
Structural analysis of spermine and magnesium ion binding to yeast phenylalanine transfer RNA.
Refinement of the diffraction data at 2.5-A resolution from orthorhombic crystals of yeast tRNAPhe has proceeded to the point where spermine and magnesium ions can be located in the difference electron density map. Two spermine molecules are found: one is located in the major groove at one end of the anticodon stem; the other is near the variable loop and curls around phosphate 10 in a region where the polynucleotide chain takes a sharp turn. Four distinct magnesium ions have been identified: one in the anticodon loop, two in the D loop, and one coordinated with phosphates 8, 9, 11, and 12, where the polynucleotide chain is coiled. The conformation of the anticodon stem and loop is stabilized by the cations at the end of the molecule. The positions of these ions may be related to aspects of the biological activity of tRNA. The spermine and magnesium ions appear to be important in maintaining the overall folding of the tRNA molecule.
Pre-proparathyroid hormone; amino acid sequence, chemical synthesis, and some biological studies of the precursor region.
The precursor of bovine proparathyroid hormone was synthesized by translation of parathyroid mRNA in a wheat-germ cell-free system. The amino acid sequence of the NH2-terminal extension (the pre sequence) was determined by repetitive Edman degradation of the polypeptide labeled with radioactive amino acids (radiosequencing). The pre sequence of pre-proparathyroid hormone is (formula: see text) which is followed by the sequence of proparathyroid hormone. It is significant that 20 of the 25 amino acids in the sequence are hydrophobic. This high hydrophobicity is consistent with the proposed role of the pre sequence as a membrane-penetrating peptide. The precursor-specific sequence of 31 amino acids was snythesized chemically by the solid-phase technique. This synthetic peptide was shown to bind to the microsomal fraction of homogenates prepared from extracts of parathyroid glands, a finding consistent with the proposed role of the precursor peptide in the attachment of the nascent chain--mRNA--ribosome complex to the endoplasmic reticulum.
Membrane proteins synthesized but not processed by isolated maize chloroplasts.
One-dimensional maps of proteolytic fragments generated by digestion with Staphylococcus aureus protease in sodium dodecyl sulfate (SDS) were used to identify three polypeptides synthesized by isolated Zea mays chloroplasts. This technique does not depend upon proper incorporation of the newly synthesized polypeptides into a more complex structure for their identification. The only preliminary purification required is electrophoretic separation on SDS-polyacrylamide gels. The pattern of radioactive fragments from labeled proteins which co-migrate with the alpha and beta subunits of chloroplast coupling factor (CF1) corresponds precisely to the pattern of stainable fragments derived from subunits of the purified enzyme. A 34,500-dalton protein is the major membrane-associated product of protein synthesis by isolated maize chloroplasts. From the similarity in the fragments formed by digestion with S. aureus protease, it appears that this radioactive protein is probably a precursor of a 32,000-dalton protein which is a component of the thylakoid. The alpha and beta subunits of CF1 newly synthesized by isolated chloroplasts are not fully extractable by procedures which normally solubilize the enzyme from membranes. The 34,500-dalton protein is not processed to the 32,000-dalton form in any great amount by isolated chloroplasts. A 19,000-dalton fragment of the 32,000-dalton protein is protected from digestion when thylakoids are treated with proteases, while the newly synthesized 34,500-dalton protein is fully susceptible. The isolated chloroplast does not appear to be able to fully integrate these newly made proteins into the membrane structure.
[Possible role of asymmetrical neutralization of DNA by histones in the folding of nucleosomal DNA].
Explore the source record for details and available documents.
DNA complementary to parathyroid mRNA directs synthesis of pre-proparathyroid hormone in a linked transcription-translation system.
DNA complementary in sequence to the messenger RNA for pre-proparathyroid hormone was synthesised using reverse transcriptase. In a linked transcription-translation system using RNA polymerase and cell-free extract from wheat germ, the DNA directed the synthesis of a protein identified as pre-proparathyroid hormone by N-terminal sequencing and by electrophoretic and immunologic criteria.
Crystallographic studies of a mitogenic lectin from pea seeds.
Explore the source record for details and available documents.
Sickle hemoglobin aggregation: a new class of inhibitors.
A number of tri- and tetrapeptides have been found to inhibit aggregation and gelation of deoxygenated sickle cell hemoglobin. These inhibitors have hydrophobic phenylalanine residues at one end and hydrogen bonding lysine or arginine side chains at the other end. The backbone is not very specific. The inhibitors do not modify the oxygen carrying properties of hemoglobin. When the inhibitor and sickle hemoglobin are put inside reconstituted cells, the erythrocytes do not sickle upon deoxygenation. Compounds of this type may develop useful agents in the therapy of sickle cell anemia.
Preliminary X-ray study of leucine aminopeptidase (bpvine lens), and oligomeric metalloenzyme.
Explore the source record for details and available documents.
Preliminary x-ray diffraction data for tetragonal crystals of trypsinized Escherichia coli elongation factor.
Explore the source record for details and available documents.
Maize chloroplast DNA fragment encoding the large subunit of ribulosebisphosphate carboxylase.
In vitro linked transcription-translation of chloroplast DNA has been used to show that the large subunit of ribulose-1,5-bisphosphate carboxylase [3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39] is encoded by Zea mays chloroplast DNA. A BamHI-generated chloroplast DNA sequence cloned in Escherichia coli is shown to direct the in vitro synthesis of this protein identified as large subunit by its size, serological properties, and limited proteolytic digestion products.
Structural organization of complexes of transfer RNAs with aminoacyl transfer RNA synthetases.
A variety of experimental data on synthetase-tRNA interactions are examined. Although these data previously had no direct explanation when viewed only in terms of the tRNA cloverleaf diagram, they can be rationalized according to a simple proposal that takes account of the three dimensional structure of tRNA. It is proposed that a major part of the binding site for most or all synthetases is along and around the diagonal side of the tRNA structure, which contains the acceptor stem, dihydrouridine stem, and anticodon. This side of the tRNA molecule contains structural features likely to be common for all tRNAs. Depending on the system, an enzyme may span a small part or all of the region of this side of the molecule. Interactions with other parts of the structure may also occur in a manner that varies from complex to complex. These interactions may be determined, in part, by the angle at which the diagonal side of the flat tRNA molecule is inserted onto the surface of the synthetase.
Annihilation of positrons in D and L isomers of various amino acids.
Explore the source record for details and available documents.
Structural domains of transfer RNA molecules.
In this article, we have described various detailed features of the conformation of yeast tRNA(Phe) revealed by recent refinement analysis of x-ray diffraction data at 2.5 A resolution. The gross features of the molecule observed in the unrefined version have been largely confirmed and a number of new features found. The unique role of the ribose 2' hydroxyl groups in maintaining a series of nonhelical conformations in this RNA molecule has become apparent. Many of these features are a direct consequence of the geometry of the ribose phosphate backbone of RNA molecules, and these may also be found in structured regions of other RNA species as well. Special attention has been directed toward two conformational motifs revealed by this analysis. These include the striking similarity between the TpsiC and anticodon hairpin turns in the polynucleotide chain, which are stabilized by the participation of uridine in the U turn. In addition, there is frequent occurrence of an arch conformation in the polynucleotide chian which is stabilized by hydrogen bonds from 2' hydroxyl residues to phosphate groups across the base of the arch. The importance of the 2' hydroxyl interactions in defining tertiary structure is illustrated by the fact that, in the nonhelical regions, almost half of the ribose residues are involved in O2' hydrogen-bonding interactions which stabilize the conformation of the molecule.
Crystallization of a DNA-unwinding protein: preliminary x-ray analysis of fd bacteriophage gene 5 product.
Explore the source record for details and available documents.