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Aspartic Acid Amino - Crossref

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Last Updated: 16 May 2022

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Substitution of a single amino acid (aspartic acid for histidine) converts the functional activity of human complement C4B to C4A.

The C4B isotype of the fourth component of human complement's 3- to 4-fold greater hemolytic activity than does its other isotype C4A. When C1 is on IgG immune aggregates, C4A binds to a greater degree. The differences in covalent binding properties between residues 1101 and 1106 -- specifically, Pro-1101, Cys-1102, Leu-1105, and Asp-1106 in C4B, respectively, are located in the C4d area of the alpha chain's C4D region. The single substitution of aspartic acid for histidine at position 1106 was largely responsible for the change in functional efficiency and structure of the chemical bond that was developed, according to a comparison of these by hemolytic assay and binding to IgG aggregates. Position 1106 is not "catalytic" as previously stated, according to this study, it interacts sterically/electrostatically with potential acceptor sites and helps to "select" binding sites on potential acceptor molecules.

Source link: https://doi.org/10.1073/pnas.87.17.6868


An aspartic acid at amino acid 108 is required to rescue infectious virus after transfection of a poliovirus cDNA containing a CGDD but not SGDD amino acid motif in 3Dpol

Previous reports from this laboratory used oligonucleotide site-directed mutation mutagenesis to replace the tyrosine amino acid at this motif with other amino acids. The viruses were recovered with 3Dpol genes with a methionine mutation at amino acid 108, resulting in a glutamic acid-to-aspartic acid change in the poliovirus RNA polymerase. Enzymes containing the 3D-D-108 mutation of the wild-type amino acid showed in vitro enzyme activity similar to that of the wild-type enzyme containing 3D-E-108. In vitro activity of polymerases containing 3D-C-326 or 3D-S-326 mutations did not change significantly in vitro activity of the polymerases containing either mutation at amino acid 3D-D-D-108. Transfections of poliovirus cDNAs with the substitution at amino acid 326 with or without the second mutation at amino acid 108 were carried out. The virus was obtained from transfection of polio-virus cDNAs containing 3D-D-108/C-326 mutation, which was replicated with kinetics similar to that of the wild-type virus. The codon for cysteine reverted to the codon for tyrosine, according to RNA sequence analysis of the region of the 3Dpol containing the 3D-C-326 mutation. Virus replication can only occur under the right conditions, according to the findings, poliovirus has the ability to revert mutations within the YGDD amino acid motif of the poliovirus 3Dpol gene, which can be reproduced by replication.

Source link: https://doi.org/10.1128/jvi.69.12.8173-8177.1995


Regulation of cephamycin C synthesis, aspartokinase, dihydrodipicolinic acid synthetase, and homoserine dehydrogenase by aspartic acid family amino acids in Streptomyces clavuligerus

Both Streptomyces clavuligerus' antibiotic production was boosted by 75% by DL-mesophorin precursors and amino acids. Streptomycetes, as other bacteria, are expected to produce lysine from aspartic acid; therefore, feedback control systems operating in S. clavuligerus' aspartic acid family pathway, which may influence the transfer of carbon to alpha-adipic acid were investigated. Threonine inhibited antibiotic growth by 41% when added to a reduced medium at a concentration of 10 mM. Threonine and lysine inhibited feedback inhibition in the aspartokinase of S. clavuligerus, a process that has been subjected to concerted feedback inhibition. Threonine can cause Threonine to reduce the supply of lysine suitable for cephamycin C biosynthesis by this concerted mechanism. It seems that S. clavuligerus aspartokinase is a significant step in the control of carbon flow toward alpha-adipic acid.

Source link: https://doi.org/10.1128/aac.21.1.74

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions