Structural studies of bovine heart cytochrome c1

The complete primary structure of bovine heart cytochrome c1 was established by analyses of peptide fragments prepared by digestion using trypsin, staphylococcal protease, and chymotrypsin and by cyanogen bromide cleavage of cytochrome c1 and its derivatives. The total number of amino acid residues is 241, giving a molecular weight of 27,924 including the heme group. The NH2- and COOH-terminal residues are serine and lysine, respectively. One characteristic of the protein is that cytochrome c1 contains 43.6% hydrophobic residues and the polarity is estimated to be 41.1%. No clear homology was found between cytochrome c1 and other membranous proteins such as cytochrome b5 or the subunits of cytochrome oxidase for which sequences have been reported. Cytochrome c1 is predicted to have a high content of alpha-helix (46%). Partial sequence studies were also carried out on cytochrome c1 preparations obtained by different procedures and showed that there is no difference among the sequences of various preparations of cytochrome c1. The presence of a hydrophobic cluster near the COOH-terminal region indicates that the COOH-terminal region of cytochrome C1 associates with, or is buried in, the phospholipid bilayer of the mitochondrial membrane.

13N isotope studies on the pathway of ammonia assimilation in Bacillus megaterium and Escherichia coli

The pathway of ammonia incorporation into amino acids was studied by use of 13N-ammonium ions in Bacillus megaterium and Escherichia coli that had been grown aerobically on a minimal salts medium containing NH4Cl as the source of nitrogen. Anion- and cation-exchange high-pressure-liquid chromatography was used to separate amino acids relevant to the several possible pathways for ammonia assimilation in bacteria. At an initial concentration of added NH4+ of 1 microM, the glutamine synthetase-glutamate synthase pathway represented the major pathway in both bacteria on the basis of the effects of inhibitors of that pathway (L-methionine-DL-sulfoximine and azaserine) and of transamination (aminooxy-acetate) and the observation that the specific activity of glutamine was greater initially than that of any other amino acid likely to be the first product of an assimilation pathway. The study provides (i) a new analytical method for 13N-tracer investigation of amino acids, (ii) confirmation of conclusions from enzymological studies on the pathway of ammonia assimilation in B. megaterium and E. coli, and (iii) proof that alanine dehydrogenase and aspartate ammonia lyase (aspartase) are not important pathways in B. megaterium at low NH4+ concentrations.

Identity of the heme-not-containing protein in bovine heart cytochrome c1 preparation with the protein mediating c1-c complex formation--a protein with high glutamic acid content

A heme-not-containing protein was isolated from cytochrome c1 preparation by gel filtration after carboxymethylation and citraconylation. The amino acid sequence of this protein was determined by the analysis of tryptic and chymotryptic peptides as well as by solid-phase sequence analysis. It consisted of 78 amino acid residues and the molecular weight was calculated to be 9,175. This protein contained a high proportion of glutamic acid and glutamine (27% of the total residues) but no methionine, isoleucine, tyrosine, and tryptophan. The most notable feature was an acidic cluster of 8 consecutive glutamic acid residues near the amino(N)-terminus). The secondary structure was predicted to have a high proportion of helical content. The amino acid composition and N-terminal sequence of a protein independently prepared from bovine heart mitochondria, which is essential to the formation of the cytochrome c1-c complex, suggested that this colorless factor and the present heme-not-containing protein are identical. Evidence shows that another protein, called the non-heme protein, isolated from "two-band" cytochrome c1 preparation is also the same protein as that presented in this paper.

Traumatic primary intraventricular hemorrhage

Two patients with primary intraventricular hemorrhage following mild head injury are presented. Both patients experienced a rapid loss of consciousness after a lucid interval following the head injury. Conray ventriculography or computerized tomography revealed intraventricular hematoma originating in the third ventricle and causing an obstructive hydrocephalus. Both patients made good recoveries promptly after ventricular drainage.

The genes for fifteen ribosomal proteins of Saccharomyces cerevisiae

We have isolated recombinant lambda phage carrying the genes for 14 of the ribosomal proteins of the yeast Saccharomyces cerevisiae. Analysis of these and of the plasmid carrying the gene tcm1, which codes for the ribosomal protein responsible for resistance to trichodermin, demonstrates that in general the genes for ribosomal proteins are unlinked. One exceptional recombinant carries the genes for two ribosomal proteins within a 2-kilobase region. DNA fragments bearing individual ribosomal protein genes were used to probe restriction digests of the yeast genome to determine whether any of the genes were duplicated. Only 3 of 12 of the genes are present unequivocally as a single copy. Similar fragments were used to probe blots of mRNA separated on denaturing agarose gels to determine the size of the mRNA for each protein. In each case, the mRNA is near the minimum size necessary to code for its protein. In certain temperature-sensitive mutants which fail to synthesize functional mRNA for ribosomal protein, Rosbash et al. (Rosbash, M., Harris, P. K. W., Woolford, J., and Teem, J. L. (1981) Cell, 24, 679-686) have demonstrated the accumulation of a larger RNA molecule, homologous to a ribosomal protein gene, that appears to be a transcript which retains an intervening sequence. We find that for 8 of the 11 ribosomal protein genes examined, a larger molecule accumulates in such a mutant strain, suggesting that in general transcripts of ribosomal protein genes may have introns.

Fenestration of the anterior cerebral artery

Three cases of angiographically demonstrated fenestration of the anterior cerebral artery are reported. Fenestration occurred at the medial half of the horizontal segment of the anterior cerebral artery in all cases. Its embryology and clinical significance are briefly discussed, and the anatomical and radiological literature on fenestration of the anterior cerebral artery is reviewed.

Mycobacterium leprae: atypical and unclassified

Once M. leprae is grown on artificial media in the test tube, it might prove to have a great variety of characteristics quite different to those expected from our knowledge of M. leprae isolated from the susceptible host. The cultures might be slow or fast growing, pigmented or colorless, pathogenic for the armadillo, or not; they might produce limited disease in the foot pad of mice, or the contrary. The in vitro M. leprae culture might or might not provoke a lepromine reaction; the culture might grow at a lower or higher temperature. It is well documented that mycobacteria show great differences in elasticity and adaptability to cultivation conditions. It is absolutely certain that once grown in a test tube, M. leprae will behave as an atypical species. However, each individual culture of M. leprae obtained in vitro will have the same drug sensitivity pattern as in the lepromatous leprosy patient from whom it was cultivated.

Hypermethioninemia in an infant

We discuss an infant with hepatitis and hypermethioninemia. An inborn error of metabolism, such as methionine adenosyltransferase deficiency or hereditary tyrosinemia, was originally thought to be the basis for these abnormalities. The infant's subsequent clinical course, however, was incompatible with such a diagnosis; the hypermethioninemia was instead due to the trilogy of prematurity, hepatitis, and a high-protein, high-methionine diet.

Spatial configuration of mRNA 5'-terminus

Nuclear magnetic resonance investigation has revealed that the 5'-terminus m7G5'ppp5'Am of mRNA displays a spatial configuration in which the bases form stacked arrays. Details of the conformation as derived from coupling constants, shift trends and ring current considerations are discussed.

A modified nephrostomy in the management of urinary fistula after renal transplantation

A technique for complete urinary diversion was used in the management of urinary fistula following renal transplantation. Nephrostomy was modified by closing the renal pelvis at the ureteropelvic junction. No impairment of renal function occurred. In the presence of infection, it is reasonable first to treat the infection and postpone the reconstructive procedure until the infection has subsided.