Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: CAS:56-41-7 (alanine)
 70,945 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The K1 killer toxin of Saccharomyces cerevisiae consists of 103- and 83-residue alpha and beta components whose derivation, from a 316-residue precursor preprotoxin, requires processing at the alpha N-terminus (after ProArg-44), the alpha C-terminus (after ArgArg-149) and at the beta N-terminus (after LysArg-233). These processing events occur after translocation to the Golgi and have been investigated using beta-lactamase fusions. Signal peptidase cleavage of the precursor, predicted to occur after Ala-26, was confirmed by N-terminal sequence analysis of Ala-34 and Ile-52 fusions. Cleavage at all of the other predicted processing sites, including ProArg-44, is dependent on activity of the Kex2 protease. A fourth Kex2-dependent cleavage occurs at LysArg-188. Implications for the specificity of Kex2 cleavage and preprotoxin processing are discussed.
Mol Microbiol 1992 Feb
PMID:Kex2-dependent processing of yeast K1 killer preprotoxin includes cleavage at ProArg-44. 156 Jul 80

The human prostate tumor cell line LNCaP contains an abnormal androgen receptor system with broad steroid binding specificity. Progestagens, estradiol and several antiandrogens compete with androgens for binding to the androgen receptor in the cells to a higher extent than in other androgen sensitive systems. Optimal growth of LNCaP cells is observed after addition of the synthetic androgen R1881 (0.1 nM). In addition, estrogens, progestagens and several antiandrogens do not inhibit androgen responsive growth, but have striking growth stimulatory effects and increase EGF receptor level and acid phosphatase secretion. We have found that the androgen receptor in the LNCaP cells contains a single point mutation changing the sense of codon 868 (Thr to Ala) in the ligand binding domain. Expression vectors containing the normal or mutated androgen receptor sequence were transfected into COS or HeLa cells. Androgens, progestagens, estrogens and several antiandrogens bind the mutated androgen receptor protein and activate the expression of an androgen-regulated reporter gene (GRE-tk-CAT), indicating that the mutation directly affects both binding specificity and the induction of gene expression. Interestingly, the antiandrogen casodex showed antiandrogenic properties in growth studies of LNCaP cells and did not induce reporter gene activity in Hela cells transfected with the mutant receptor. The mutated androgen receptor of LNCaP cells is therefore a useful tool in the elucidation of different levels of action of steroids and antisteroids.
J Steroid Biochem Mol Biol 1992 Mar
PMID:The androgen receptor in LNCaP cells contains a mutation in the ligand binding domain which affects steroid binding characteristics and response to antiandrogens. 156 39

The theory for measuring co-operativity between interactions in proteins by protein engineering experiments is developed by introducing a procedure for analysing increasing orders of synergy in a protein with increasing numbers of residues. The (pairwise) interaction energy (delta 2Gint) between two side-chains may be measured experimentally by a double-mutant cycle consisting of the wild-type protein, the two single mutants and the double mutant. This procedure may be extended to three residues to give a value for delta 3Gint for a triple-mutant cube, and to higher orders using multi-dimensional mutant space. We now show that delta 3Gint is the excess energy of adding all three chains compared with the sum of all the pairwise values of delta 2Gint for each of the constituent double-mutant cycles and the sum of all the single addition energies. This physical interpretation extends to higher orders of mutation. delta nGint (i.e. the interaction energy for n residues), thus, reveals the layers of synergy in interactions as a protein is built up. This procedure is applied to measuring changes in synergy during the refolding of barnase for the triad of salt-linked residues Asp8, Asp12 and Arg110, which are mutated to alanine residues. The value of delta 3Gint in the folded structure is 0.77(+/- 0.06) kcal mol-1 (i.e. the triad is 0.77 kcal mol-1 more stable than expected from the sum of the individual pairwise interactions and single contributions). The value of delta 3Gint is still significant in the transition state for unfolding (0.60(+/- 0.07) kcal mol-1) and in the folding intermediate (0.60(+/- 0.13 kcal mol-1)). These results show that synergistic interactions exist in barnase, in its transition state for unfolding and in a refolding intermediate. A direct measurement of the change of co-operativity between the folded state and the transition state for unfolding shows a decrease of 0.17(+/- 0.04) kcal mol-1, suggesting that the initial stages of protein unfolding may be accompanied by some loosening of structure in parts that still interact. The similar extent of co-operativity in the transition state for unfolding and the intermediate in refolding suggests that the intermediate is homogeneous, at least in the region of the salt-linked triad, as heterogeneity would lower the co-operativity.
J Mol Biol 1992 Apr 05
PMID:Co-operative interactions during protein folding. 156 52

The affinity of an antibody for its ligand 2-phenyloxazolone was improved by protein design. For the design two-dimensional nuclear magnetic resonance spectroscopy, protein engineering and molecular modelling were used in an interactive scheme. Initially the binding site was localized with the help of transferred nuclear Overhauser enhancement signals from two, site specifically assigned tyrosine side-chains in the complementarity-determining regions of the antibody to the ligand 4-glycyl-2-phenyloxazolone. On their basis the hapten was placed into a model of the Fv-fragment built according to the principles of canonical antibody structures. From the model, unfavourable contacts between hapten and an aspartyl side-chain in complementarity-determining region 3 of the heavy chain were predicted. Substitution of the aspartyl residue by alanine resulted in a threefold increase in affinity of the antibody Fv-fragment for two hapten derivatives when compared with the wild-type. Nuclear magnetic resonance analysis of the improved Fv-fragment revealed an interaction between the alpha-carbon proton of alanyl residue with the ligand, which was not seen for the aspartyl residue. This interaction is not entirely in accordance with the model, which predicts an interaction between the side-chain of this residue and the hapten. However, it shows that by combined use of nuclear magnetic resonance analysis and molecular modelling, a residue that is critical for antigen binding was identified, whose mutation allowed the design of an improved antibody combining site.
J Mol Biol 1992 Apr 20
PMID:Improving the antigen affinity of an antibody Fv-fragment by protein design. 156 79

The triple-helical conformation has the stringent amino acid sequence constraint that every third residue must be a glycine, (X-Y-Gly)n. We use nuclear magnetic resonance and circular dichroism to quantify the consequences of a substitution in the glycine position of a triple-helical peptide, and to enhance our understanding of interactions in this basic structural motif. A 30-residue peptide with a Gly----Ala change forms a stable trimer at a folding rate somewhat less than that of the unsubstituted peptide, and the substitution results in a marked decrease in thermal stability and a conformational perturbation of about 30% of the triple-helical structure. Two models were generated for this peptide, one with the alanine residues packed inside the triple helix and one with a looping out of the chain at the substitution site. Studies on the Gly----Ala peptide are useful in understanding connective tissue diseases which result from the substitution of one glycine residue in the triple-helix of fibrillar collagens.
J Mol Biol 1992 May 05
PMID:Nuclear magnetic resonance and circular dichroism studies of a triple-helical peptide with a glycine substitution. 158 83

Measurements of the tissue accumulation of alpha-amino[1-14C]isobutyrate [1-14C]AIB in lean (+/?) and obese (fa/fa) Zucker rats showed an augmented tissue/plasma ratio in the liver of the obese animals. In contrast, brown adipose tissue AIB accumulation was lower in the fa/fa animals. In response to a 24 h starvation period AIB accumulation was significantly elevated in the liver and plasma of the lean animals and was unchanged in the liver of the fa/fa animals. The circulating concentration of alanine and branched-chain amino acids was elevated in the fa/fa animals as compared to their lean counterparts. These observations suggest that amino acid uptake is not involved in the impaired muscle development observed in the obese Zucker rat and that the ability of brown adipose tissue for amino acid utilization is decreased in the obese animals suggesting that this may partially explain the impaired thermoregulatory capacity observed in brown adipose tissue of obese Zucker rats.
Mol Cell Biochem 1992 Mar 25
PMID:Amino acid metabolism in several tissues of the obese Zucker rat as indicated by the tissue accumulation of alpha-amino[1-14C]isobutyrate. 158 4

The region of the Bacillus subtilis 168 chromosome that contains the structural genes for the major vegetative cell autolysin, (N-acetyl-muramoyl-L-alanine amidase), and its modifier protein has been cloned. Insertional mutagenesis with integrative plasmids carrying small DNA fragments from this region has revealed that both genes are located on a 4 kb fragment; they are organised in one transcription unit, the modifier being transcribed first. Studies of derivatives in which either the amidase or the modifier or both proteins are inactivated have revealed that amidase-deficient strains are not affected in growth, cell separation, transformability or sporulation. Observed phenotypic differences were altered kinetics of, cell wall turn-over and a reduced rate of, autolysis of native cell wall preparations. A residual amidase activity, about 3% of that of the wild-type strain, was found in strains devoid of the major amidase. A new, distinct cell wall-bound protein, designated CWBP49', with the same molecular weight as the amidase, was identified in mutants devoid of the latter enzyme.
Mol Gen Genet 1992 Apr
PMID:Identification of the structural genes for N-acetylmuramoyl-L-alanine amidase and its modifier in Bacillus subtilis 168: inactivation of these genes by insertional mutagenesis has no effect on growth or cell separation. 158 6

A region of substantial homology, comprising 32 amino acids around a highly conserved glycine residue, is located near the C-terminal ends of the hydrophobic Fhu, Fec, Fep, Fat, and Btu transport proteins involved in the uptake of ferrisiderophores and vitamin B12 into Escherichia coli and Vibrio anguillarum. Furthermore, a region similar in location and sequence containing an invariant glycine at an equivalent position was identified in the hydrophobic component of all other periplasmic binding protein-dependent (PBT) systems. In the FhuB protein, which is twice the size of the other PBT-related inner membrane proteins and which displays an internal homology, two conserved glycine residues are present. Alteration of Gly at positions 226 and 559 to Ala, Val, or Glu reduced iron(III) hydroxamate uptake, suggesting that this homologous region may play a general role in the mechanism of PBT-dependent transport.
Mol Gen Genet 1992 Apr
PMID:Point mutations in two conserved glycine residues within the integral membrane protein FhuB affect iron(III) hydroxamate transport. 158 8

The specificity of interaction of amino acids with triplets in the acceptor helix stem of tRNA was investigated by means of a statistical analysis of 1400 tRNA sequences. The imprint of a prototypic genetic code at position 3-5 of the acceptor helix was detected, but only for those major amino acids, glycine, alanine, aspartic acid, and valine, that are formed by spark discharges of simple gases in the laboratory. Although remnants of the code at position 3-5 are typical for tRNAs of archaebacteria, eubacteria, and chloroplasts, eukaryotes do not seem to contain this code, and mitochondria take up an intermediary position. A duplication mechanism for the transposition of the original 3-5 code toward its present position in the anticodon stem of tRNA is proposed. From this viewpoint, the mode of evolution of mRNA and functional ribosomes becomes more understandable.
J Mol Evol 1992 Jun
PMID:Statistical evidence for remnants of the primordial code in the acceptor stem of prokaryotic transfer RNA. 159 40

Sequences of 47 members of the Zn-containing alcohol dehydrogenase (ADH) family were aligned progressively, and an evolutionary tree with detailed branch order and branch lengths was produced. The alignment shows that only 9 amino acid residues (of 374 in the horse liver ADH sequence) are conserved in this family; these include eight Gly and one Val with structural roles. Three residues that bind the catalytic Zn and modulate its electrostatic environment are conserved in 45 members. Asp 223, which determines specificity for NAD, is found in all but the two NADP-dependent enzymes, which have Gly or Ala. Ser or Thr 48, which makes a hydrogen bond to the substrate, is present in 46 members. The four Cys ligands for the structural zinc are conserved except in zeta-crystallin, the sorbitol dehydrogenases, and two bacterial enzymes. Analysis of the evolutionary tree gives estimates of the times of divergence for different animal ADHs. The human class II (pi) and class III (chi) ADHs probably diverged about 630 million years ago, and the newly identified human ADH6 appeared about 520 million years ago, implying that these classes of enzymes may exist or have existed in all vertebrates. The human class I ADH isoenzymes (alpha, beta, and gamma) diverged about 80 million years ago, suggesting that these isoenzymes may exist or have existed in all primates. Analysis of branch lengths shows that these plant ADHs are more conserved than the animal ones and that class III ADHs are more conserved than class I ADHs. The rate of acceptance of point mutations (PAM units) shows that selection pressure has existed for ADHs, implying that these enzymes play definite metabolic roles.
J Mol Evol 1992 Jun
PMID:Progressive sequence alignment and molecular evolution of the Zn-containing alcohol dehydrogenase family. 159 44


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