scholarly journals Primary Structure of Apovitellenin I From Hen Egg Yolk and its Comparison With Emu Apovitellenin I

1976 ◽  
Vol 29 (3) ◽  
pp. 175 ◽  
Author(s):  
TAA Dopheide ◽  
AS Inglis
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Primary Structure ◽  
Egg Yolk ◽  
Structure And Function ◽  
Single Base ◽  
Hen Egg Yolk ◽  
Considerable Homology ◽  
And Function ◽  
Hen Egg

The amino acid sequence of apovitellenin I from hen egg yolk has been determined using both automatic and manual procedures; it comprises 82 residues. Hen apovitellenin shows considerable homology with emu apovitellenin I which contains 84 residues. Besides two deletions in the sequence, the hen protein differs in 28 positions from the emu protein; 26 of these positions may have arisen from single base changes. The changes are largely conservative ones, which suggest that the structure and function have been preserved despite extensive mutation.

Chitosanase from Streptomyces sp. strain N174: a comparative review of its structure and function

1997 ◽  
Vol 75 (6) ◽  
pp. 687-696 ◽  
Author(s):  
Tamo Fukamizo ◽  
Ryszard Brzezinski
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Substrate Binding ◽  
Structure And Function ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Streptomyces Sp ◽  
Binding Cleft ◽  
And Function

Novel information on the structure and function of chitosanase, which hydrolyzes the beta -1,4-glycosidic linkage of chitosan, has accumulated in recent years. The cloning of the chitosanase gene from Streptomyces sp. strain N174 and the establishment of an efficient expression system using Streptomyces lividans TK24 have contributed to these advances. Amino acid sequence comparisons of the chitosanases that have been sequenced to date revealed a significant homology in the N-terminal module. From energy minimization based on the X-ray crystal structure of Streptomyces sp. strain N174 chitosanase, the substrate binding cleft of this enzyme was estimated to be composed of six monosaccharide binding subsites. The hydrolytic reaction takes place at the center of the binding cleft with an inverting mechanism. Site-directed mutagenesis of the carboxylic amino acid residues that are conserved revealed that Glu-22 and Asp-40 are the catalytic residues. The tryptophan residues in the chitosanase do not participate directly in the substrate binding but stabilize the protein structure by interacting with hydrophobic and carboxylic side chains of the other amino acid residues. Structural and functional similarities were found between chitosanase, barley chitinase, bacteriophage T4 lysozyme, and goose egg white lysozyme, even though these proteins share no sequence similarities. This information can be helpful for the design of new chitinolytic enzymes that can be applied to carbohydrate engineering, biological control of phytopathogens, and other fields including chitinous polysaccharide degradation. Key words: chitosanase, amino acid sequence, overexpression system, reaction mechanism, site-directed mutagenesis.

scholarly journals High-grade mutant OmpF induces decreased bacterial survival rate.

2014 ◽  
Vol 61 (2) ◽  
Author(s):  
Zhi-ping Zhao ◽  
Ting-ting Liu ◽  
Li Zhang ◽  
Min Luo ◽  
Xin Nie ◽  
...  
Keyword(s):  
Amino Acid ◽  
Survival Rate ◽  
Sequence Analysis ◽  
Amino Acid Sequence ◽  
Inhibition Zone ◽  
Structure And Function ◽  
High Grade ◽  
Bacterial Survival ◽  
Antibiotic Inhibition ◽  
And Function

OmpF plays very important roles in the influx of antibiotics and bacterial survival in the presence of antibiotics. However, high-grade mutant OmpF and its function in decreasing bacterial survival rate have not been reported to date. In the present study, we cloned a high-grade mutant OmpF (mOmpF) and sequence analysis suggested that over 45 percent of the DNA sequence was significantly mutated, leading to dramatic changes in over 55 percent of the amino acid sequence. mOmpF protein was successfully expressed. When grown in the presence of antibiotic, the bacterial survival rate decreased and the antibiotic inhibition zone became larger with the increase of the mOmpF. It was concluded that concentration of high-grade mutant mOmpF dramatically influenced the bacterial survival rate. The study presented here may provide insights into better understanding of the relationships between structure and function of OmpF.

The amino acid sequence of wheat β-purothionin

1976 ◽  
Vol 54 (10) ◽  
pp. 835-842 ◽  
Author(s):  
A. S. Mak ◽  
B. L. Jones
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Primary Structure ◽  
Basic Protein ◽  
Viscum Album ◽  
Low Molecular Weight ◽  
Amino Acid Residues ◽  
Basic Proteins ◽  
Considerable Homology

The complete amino acid sequence of β-purothionin, a low molecular weight, very basic, protein isolated from wheat endosperm material, has been determined. β-purothionin is toxic to some bacteria, to yeasts, and to animals when injected. The protein contains 45 amino acid residues and has a molecular weight of 4913. The 8 cysteine and 10 basic residues are distributed throughout the molecule. The primary structure of the protein shows considerable homology to those of the viscotoxins, which are toxic, small, basic proteins found in the leaves and stems of European mistletoe (Viscum album L.).

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