• BMB Reports
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• v.28 no.2
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• pp.124-128
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• 1995

Biodegradative threonine dehydratase purified from Serratia marcescens ATCC 25419 was inactivated by the arginine specific modification reagent, phenylglyoxal (PGO) and the lysine modification reagent, pyridoxal 5'-phosphate (PLP). The inactivation by PGO was protected by L-threonine and L-serine. The second order rate constant for the inactivation of the enzyme by PGO was calculated to be 136 $M^{-1}min^{-1}$. The reaction order with respect to PGO was 0.83. The inactivation of the enzyme by PGO was reversed upon addition of excess hydroxylamine. The inactivation of the enzyme by PLP was protected by L-threonine, L-serine, and a-aminobutyrate. The second order rate constant for the inactivation of the enzyme by PLP was 157 $M^{-1}min^{-1}$ and the order of reaction with respect to PLP was 1.0. The inactivation of the enzyme by PLP was reversed upon addition of excess acetic anhydride. Other chemical modification reagents such as N-ethylmaleimide, 5,5'-dithiobis (2-nitrobenzoate), iodoacetamide, sodium azide, phenylmethyl sulfonylfluoride and diethylpyrocarbonate had no effect on the enzyme activity. These results suggest that essential arginine and lysine residues may be located at or near the active site.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.2
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• pp.88-94
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• 2015

Bub1 is one of the spindle checkpoint proteins and plays a role in recruitment of the related proteins to kinetochore. Here, we studied the structural characteristic of the evolutionarily conserved 160 amino acid region in the N-terminus (hBub1 CD1), using Circular Dichroism (CD) and NMR. Our CD results showed that hBub1 CD1 is a highly helical protein and its structure was affected by pH: as pH was elevated to basic pH, the helical propensity increased. This could be related to the surface charge of the hBub1 CD1. However, the structural change did not largely depend on the salt concentration, though the thermal stability a little increased. The previous NMR analysis revealed that the hBub1 CD1 adopts eight helices, which is consistent with the CD result. Our result would be helpful for evaluating the molecular mechanism of the hBub1 CD1 and protein-protein interactions.

• BMB Reports
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• v.39 no.2
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• pp.150-157
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• 2006

Native grass carp (Ctenopharygodon idellus) growth hormone, has 5 cysteine amino acid residues, forms two disulphide bridges in its mature form. Recombinant grass carp growth hormone, when over-expressed in E. coli, forms inclusion bodies. In vitro oxidative renaturation of guanidine-hydrochloride dissolved recombinant grass carp growth hormone was achieved by sequential dilution and stepwise dialysis at pH 8.5. The redox potential of the refolding cocktail was maintained by glutathione disulphide/glutathione couple. The oxidative refolded protein is heterogeneous, and contains multimers, oligomers and monomers. The presence of non-disulphide-bond-forming cysteine in recombinant grass carp growth hormone enhances intermolecular disulphide bond formation and also non-native intramolecular disulphide bond formation during protein folding. The non-disulphide-bond-forming cysteine was converted to serine by PCR-mediated site-directed mutagenesis. The resulting 4-cysteine grass carp growth hormone has improved in vitro oxidative refolding properties when studied by gel filtration and reverse phase chromatography. The refolded 4-cysteine form has less hydrophobic aggregate and has only one monomeric isoform. Both refolded 4-cysteine and 5-cystiene forms are active in radioreceptor binding assay.

• Journal of Sericultural and Entomological Science
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• v.39 no.1
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• pp.44-55
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• 1997

This study was carried out to find out the relationship between qualities and contraction phenomenon of silk fibers by treatment of concentrated neutral salts. The contraction effects of silk fibers showed the critical point on the treatment conditions of concentration, temperature and time, among three kinds of neutral salts such as calcium nitrate, calcium chloride and lithium bromide. But, The silk fibers, pretreated with bromide and/or formaldehyde, did not show the contraction upon treating with calcium nitrate. This indicates that tyrosine and serine can be correlated with the contraction reaction because of coupling these amino acids with bromide and formaldehyde. In conclusion, a mechanism for the contraction of silk fiber with highly concentrated calcium nitrate solution is supposed as follows. At the initial stage of ration, the water was penetrated into the amorphous regions and fibers swollen, therefore, the contraction took place mainly in amorphous regions, which have plenty of functional groups with hydroxyl residues. Then, as the calcium nitrate is penetrated into the microfibril, the gydrogen bonds of tyrosine and serine residues and broken and crystalline regions are more and more influenced by increasing concentration of calcium nitrate solution. Microgibrils of crystalline regions become entangled, contracted to linear direction and rearranged to form new stable hydrogen bonds.

• Journal of Microbiology and Biotechnology
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• v.21 no.2
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• pp.129-135
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• 2011

Cloning and characterization of the gene encoding a solvent-tolerant protease from the haloalkaliphilic bacterium Geomicrobium sp. EMB2 are described. Primers designed based on the N-terminal amino acid sequence of the purified EMB2 protease helped in the amplification of a 1,505-bp open reading frame that had a coding potential of a 42.7-kDa polypeptide. The deduced EMB2 protein contained a 35.4-kDa mature protein of 311 residues, with a high proportion of acidic amino acid residues. Phylogenetic analysis placed the EMB2 gene close to a known serine protease from Bacillus clausii KSM-K16. Primary sequence analysis indicated a hydrophobic inclination of the protein; and the 3D structure modeling elucidated a relatively higher percentage of small (glycine, alanine, and valine) and borderline (serine and threonine) hydrophobic residues on its surface. The structure analysis also highlighted enrichment of acidic residues at the cost of basic residues. The study indicated that solvent and salt stabilities in Geomicrobium sp. protease may be accorded to different structural features; that is, the presence of a number of small hydrophobic amino acid residues on the surface and a higher content of acidic amino acid residues, respectively.

• Analytical Science and Technology
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• v.7 no.2
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• pp.165-171
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• 1994

The effect of the chemical carcinogen dimetylnitrosamine(DMN) on the composition of amino acids of the liver in hamsters orally administered with DMN was studied by using the reversed phase high performance liquid chromatography technique. In the liver, the concentration of aspartic acid, glycine, glutamine, histidine, proline, tyrosine and leucine were increased ca. 2-fold of those observed in liver of control group, valine and tryptophan were increased ca. 3-fold, phenylalanine was markedly increased ca. 10-fold, whereas the concentration of threonine was decreased, serine, alanine, arginine, methionine, isoleucine and lysine were unchanged, respectively.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.75-80
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• 2004

This research was conducted to predict taste of barley kanjang using multiple regression analysis between taste components and sensory score. In the analysis of single correlation, the correlation coefficient of proline, alanine, Methionine, lysine, histidine, lavulinic acid, ${\alpha}$-ketogutaric acid was significant in 5% level. On the other hand, the taste of barley kanjang was not significantly effected by threonine, serine, cystein, phenylalanine, succinic acid, arabinose, xylose, and sucrose. It was impossible to measure taste of kanjang with barley bran to use simple correlation analysis. The 93% of barley kanjang taste was predicted using multiple regression analysis with taste components and sensory evaluation scores.

• Applied Biological Chemistry
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• v.36 no.4
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• pp.255-259
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• 1993

Chitobiase from Aeromonas salmonicida YA7-625 was purified from culture broth through ammonium sulfate precipitation, chitin affinity adsorption, hydroxylapatite column chromatography and gel filtration, with 47.2% yield and 31.5 fold purity. The molecular weight of purified chitobiase was 15,000 daltons, and the chitobiase showes maximum activity at the condition of at $40^{\circ}C$ and pH 6.0. The effects of various metal ions and inhibitors show thatcystein, glutamic acid, serine, tryptophan, and tyrosine residues seem to be concerned in chitobiase activity.

• Journal of Nutrition and Health
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• v.10 no.4
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• pp.97-103
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• 1977

Changes of free amino acids as taste compounds during the fermentation of oyster were analyzed by amino acid autoanalyzer. In fresh oyster, taurine, glutamic acid and alanine were abundant amino acids and the amounts of taurine (731mg%, on moisture and salt free base), glutamic acid (365mg%) and alanine (345.4mg% ) were 63.8% of the total free amino acids. Cystine, isoleucine, phenylalanine, leucine and histidine were detected as less abundant free amino acids and the amount of those amino. acids ranged from 5. 5mg% (cystine) to 32.9mg% (histidine). The free amino acids analyzed in this experiment were not changed in composition hut changed in amounts during 124 days of fermentation. Aspartic acid and leucine were continually increased during 124 days of fermentation. Lysine, histidine, threonine, serine, glutamic acid, tyrosine and phenyalanine were increased unlit 68 days of fermentation and than decreased gradually. The increase of arginine, glycine, valine and isoleucine were fluctuated. Taurine were dramatically decreased during the 124 days of fermentation. It is believed that glutamic acid, alanine, lecuine, serine, Iysine and threonine play an important role as taste compounds in fermented oyster because those amino acids were most abundant in fermented oyster.

• Journal of Microbiology and Biotechnology
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• v.10 no.2
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• pp.181-186
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• 2000

MAPI (microbial alkaline protease inhibitor) was isolated from cultrue broth of Streptomyces chromofuscus SMF28. The Ki values of MAPI for the representative serine proteases such as chymotrypsin and proteinase K were 0.28 and $0.63{\;}\mu\textrm{M}$, respectively, and for the cysteine proteases cathepsin B and papain were 0.66 and $0.28{\;}\mu\textrm{M}$, respectively. These data indicate that MAPI is not a potent selective inhibitor of serine or cysteine proteases. Progress curves for the inhibition of three proteases by MAPI exhibithe characteristic patterns; MAPI exhibited slow-binding inhibition of cathepsin B. It was rapidly associated with chymotrypsin before the addition of substrate and then reactivation of MAPI-inhibited enzyme was investigated in the presence of substrate. On the other hand, MAPI-proteinase K interaction was typical for those classical inhibitors. When MAPI was incubated with trypsin, there was an extensive reduction in the ingibitory activities of MAPI corresponding to 66.5% inactivation of MAPI, indicating that trypsin-like protease may play a role in the decrease of the inhibitory activity during cultivation.