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Biomedical subjects

C E Cameron

Publications and source records attributed to C E Cameron.

40 records · Page 3Linked to original sources
PubMed1992

Analysis of substrate interactions of the Rous sarcoma virus wild type and mutant proteases and human immunodeficiency virus-1 protease using a set of systematically altered peptide substrates.

In the preceding study, mutant Rous sarcoma virus (RSV) proteases are described in which three amino acids found in the human immunodeficiency virus-1 (HIV-1) protease (PR) were substituted into structurally comparable positions (Grinde, B., Cameron, C.E., Leis, J., Weber, I., Wlodawer, A., Burstein, H., Bizub, D., and Skalka, A. M. (1992) J. Biol. Chem. 267, 9481-9490). In this report, the activity of the wild type and these mutant PRs are compared using a set of RSV NC-PR peptide substrates with single amino acid substitutions in each of the P4 to P3' positions. With most substrates, the relative activities of the two active mutants followed that of the RSV PR. Substitutions in the P1 and P1' positions were an exception; in this case, the mutants behaved more like the HIV-1 PR. These results confirm predictions from structural analyses which indicate that residues 105 and 106 of the RSV PR are important in forming the S1 and S1' binding subsites. These results, further analyzed with the aid of computer modeling of the RSV PR with different substrates, provide an explanation for why only partial HIV-1 PR-like behavior was introduced into the above RSV PR mutants.

Amino Acid Sequence↗
PubMed1991

A range of catalytic efficiencies with avian retroviral protease subunits genetically linked to form single polypeptide chains.

Molecular modeling based on the crystal structure of the Rous sarcoma virus (RSV) protease dimer has been used to link the two identical subunits of this enzyme into a functional, single polypeptide chain resembling the nonviral aspartic proteases. Six different linkages were selected to test the importance of different interactions between the amino acids at the amino and carboxyl termini of the two subunits. These linkages were introduced into molecular clones of fused protease genes and the linked protease dimers were expressed in Escherichia coli and purified. Catalytically active proteins were obtained from the inclusion body fraction after renaturation. The linked protease dimers exhibited a 10-20-fold range in catalytic efficiencies (Vmax/Km) on peptide substrates. Both flexibility and ionic interactions in the linkage region affect catalytic efficiency. Some of the linked protease dimers were 2-3-fold more active than the nonlinked enzyme purified from bacteria, although substrate specificities were unchanged. Similar relative efficiencies were observed using a polyprotein precursor as substrate. Mutation of one catalytic Asp in the most active linked protease dimer inactivated the enzyme, demonstrating that these proteins function as single polypeptide chains rather than as multimers.

Avian Sarcoma Viruses↗
PubMed1976

The cracked tooth syndrome: additional findings.

The results of this study add to the previous findings on the cracked tooth syndrome. Treatment to prevent further cracking is a must. Dentists should be aware of the syndrome and, after making the diagnosis, initiate necessary treatment.

Adolescent↗