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A Anderson

Publications and source records attributed to A Anderson.

At least 145 records · Page 8Linked to original sources
PubMed1991

H-ras-1 polymorphism in leukemia.

We have examined leukocyte DNAs obtained from 21 patients with various types of leukemia for the Sacl polymorphism of H-ras-1. The patients included ten with B-lineage leukemia, two with T-cell leukemia, and nine with acute myelogenous leukemia. Using a genomic probe for H-ras-1 in Southern hybridizations, we found that 78% of the DNA from leukemias of myeloid origin were heterozygous. In contrast, only three of ten B-cell-derived leukemias showed heterozygosity. This difference in the number of heterozygotes vs. homozygotes in the two patient samples studied is statistically significant (P = 0.04 by Fisher's exact test). These results suggest the possibility that the H-ras-1 allelic pattern that is associated with acute myelogenous leukemia is distinct from that found in B-cell-derived malignancies.

Genes, ras↗
PubMed1991

Proline in alpha-helix: stability and conformation studied by dynamics simulation.

Free-energy simulations have been used to estimate the change in the conformational stability of short polyalanine alpha-helices when one of the alanines is replaced by a proline residue. For substituting proline in the middle of the helix the change in free energy of folding (delta delta G degrees) was calculated as 14 kJ/mol (3.4 kcal/mol), in excellent agreement with the one available experimental value. The helix containing proline was found to be strongly kinked; the free energy for reducing the angle of the kink from 40 degrees to 15 degrees was calculated, and found to be small. A tendency to alternate hydrogen bonding schemes was observed in the proline-containing helix. These observations for the oligopeptide agree well with the observation of a range of kink angles (18-35 degrees) and variety of hydrogen bonding schemes, in the rare instances where proline occurs in helices in globular proteins. For substituting proline at the N-terminus of the helix the change in free energy of folding (delta delta G degrees) was calculated as -4 kJ/mol in the first helical position (N1) and +6 kJ/mol in the second helical position (N2). The observed frequent occurrence of proline in position N1 in alpha-helices in proteins therefore has its origin in stability differences of secondary structure. The conclusion reached here that proline may be a better helix former in position N1 than (even) alanine, and thus be a helix initiator may be testable experimentally by measurements of fraction helical conformation of individual residues in oligopeptides of appropriate sequence. The relevance of these results in regards to the frequent occurrence of proline-containing helices in certain membrane proteins is discussed.

Alanine↗
PubMed1990

Alternative splicing of mRNA encoding rat liver cytochrome P450e (P450IIB2).

Cytochrome P450e (P450IIB2) is a phenobarbital(PB)-inducible member of the rat liver P450IIB subfamily. Among P450 cDNA clones previously isolated from a cDNA library made from the liver of a single rat were several that contained P450e inserts, including PB13, PB16, and PB22. By nucleotide sequence analysis, the PB16 and PB22 inserts have now been found to contain an additional 24-bp segment not present in the PB13 insert or in previously reported P450e-coding sequences. According to the published P450e genomic sequence, the 24-bp segment is exactly at the junction of the fifth and the sixth exons and its sequence is identical to the first 24 bp of the fifth intron. Translation of this segment would add 8 amino acid residues to the P450e protein. To detect the alternatively spliced P450e mRNA, a synthetic oligodeoxyribonucleotide (oligo) corresponding to 18 of the 24 bp of the intronic sequence found in the PB16 and PB22 inserts was made. This oligo hybridized with a 2.1-kb RNA on Northern blots of liver RNA from PB- or Aroclor 1254-treated rats. Taken together, these results indicate that individual rats can possess both forms of P450e mRNA and that an alternative splicing mechanism is responsible for their formation.

Amino Acid Sequence↗