• Asian-Australasian Journal of Animal Sciences
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• v.14 no.3
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• pp.351-357
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• 2001

The rapid formation of a cream line cannot be observed in raw goat's milk standing at a low temperature. Although the poor creaming ability of goat's milk has been considered to be due to the small size of milk fat globules and the lack of euglobulin capable of being adsorbed on milk fat globules, there is much left to study. The present work attempted to elucidate a factor for poor creaming ability of goat's milk. The creaming ability of the experimental milks reconstituted from creams and skim milks separated from cow's milk or goat's milk was measured by the volume of the cream layer and the fat content of bottom layer. The polypeptides composition of the P1 the fraction (i.e., the high molecular weight fraction eluted near the void volume obtained by the gel filtration of whey) and milk fat globule membrane prepared from both milks were compared. It was found that the promotion of creaming originated from goat's skim milk was lower than that from cow's skim milk. The P1 fraction in goat's skim milk was less than that in cow's skim milk. The polypeptide (M.W. $4.3{\times}10^4$), found in the P1 fraction of cow's milk was not found in the P1 fraction of goat's milk. It is suggested that the poor creaming ability of goat milk is caused mainly by the difference from cow milk in the amount and the composition of the P1 fraction.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.1
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• pp.52-58
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• 1995

5-methyltryptophan（5MT） resistant mutant plants （MRl） were analyzed for characterization of anthranilate synthetase （AS） and tryptophan synthetase （TS） enzymes. The enzyme was measured in crude extracts from MR1 and control seedlings of Danggin inbred line. There was no significant difference in the level of AS between MR1 and control seedlings when grown on MS medium without 5MT. However, MR1 seedlings grown on MS medium with 25mg/L 5MT showed the level of AS twice higher than that of control seedlings. The activity of AS was inhibited to 50％ in untreated plants when 4mg /L L-tryptophan was added to their extracts. Extracts from MR1 plants required about four times higher concentration of amino acid to cause equal inhibition. In the TS assay, the activity observed in MR1 seedlings was four times higher than that of control seedlings. We have also isolated and sequenced the gene which encoding the tryptophan synthetase B subunit （TSB） from maize. The gene encodes polypeptides with high homology to TSB isolated from other plants, and is expressed in all the developmental stages examined. Northern hybridization analysis indicated that the gene expression in MR1 seedlings grown on MS medium showed a higher level than in control seedlings.

• Journal of Sericultural and Entomological Science
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• v.34 no.1
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• pp.41-48
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• 1992

Dissolution and degradation of the parasporal crystal proteins produced from B. thuringiensis var. kurstaki, B. thuringiensis var. dendrolimus and B. thuringiensis var. aizawai were investigated. SDS-polyacrylamide gel electrophoresis analysis showed that the crystals contained major protein with molecular weight of approximately 134 kDa for B. thuringiensis var. aizawai 143 kDa for B. thuringiensis var. kurstaki and 149 kDa for B. thuringiensis var. dendrolimus, respectively. Crystals of three other strains were incubated alkali solutions at various pH or gut juice of Silkwarm Bombyx mori, Fall webworm Hyphantria cunea, and Common Cabbage worm Pieris rapae. When crystals of these strains were solubilized by alkali solutions, no major differences among strains B. thuringiensis could be detected. Among the strains studied, crystal protins (130-66 kDa) consist of protease resistant polypeptides in the 45-66 kDa size range when treated with gut juice of three insect species.

• Korean Journal of Plant Tissue Culture
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• v.22 no.1
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• pp.15-28
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• 1995

In order to identify an antifreeze proteins responsible for freeze-tolerance in barley the proteins accumulated in extracellular space during cold acclimination were extracted and analyzed. After 42 days cold treatment there were several proteins sized of 70, 21, 16, 14 KDa increased in their amount accumulated in extracellular space. In addition, continuously sized polypeptides smaller than 10 KDa were found to be increased in their amount as cold treatment prolongs. Since these proteins were not detectable in total leaf protein extract it appears that the procedure used to isolate extracellular extract was valid. A similarity in profile of the extracellular proteins isolated from barley and rye may indicate a possibility for these proteins to be an antifreeze proteins since the same extract from rye was reported to show an antifreezing activity.

• BMB Reports
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• v.34 no.2
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• pp.150-155
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• 2001

The mosquito-larvicidal Cry4B protein from Bacillus thuringiensis subsp. israelensds was expressed in Escherichia coli. Upon activation by trypsin, the 130-kDa protoxin was processed into the 65-kDa active toxin containing two polypeptide fragments of ca. 47 and ca. 20 kDa. These two polypeptides are products of internal cleavages on the exposed loop connecting helices 5 and 6 in the seven-helical bundle domain. PCR-based mutagenesis was employed to introduce an additional cleavage site into the loop connecting helices 3 and 4. A series of amino acid changes were introduced into the targeted loop, resulting in seven mutant protoxins. Upon digestion with trypsin, a group of mutants with arginine introduced into the loop (EPRNQ, EPNRNQ, EPRNP, ESRNP and SSRNP) produced polypeptide products similar to those of the wild type (EPNNQ). When the loop, SSRNP, was expanded by an insertion of either asparagine (NSSRNP) or valine (VSSRNP), an additional cleavage was detected with proteolytic products of 47,12 and 6 kDa. This cleavage was confirmed to be at the introduced arginine residue by N-terminal sequencing. The mosquito larvicidal assay against Aedes aegypti demonstrated a relatively unchanged toxicity for the mutants without cleavage and reduced toxicity for those with an additional cleavage.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1182-1189
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• 2004

Cytosine deaminase (cytosine aminohydrolase, EC 3.5.4.1) stoichiometrically catalyzes the hydrolytic deamination of cytosine and 5-fluorocytosine to uracil and 5-fluorouracil, respectively. The intracellular cytosine deaminase from Chromobacterium violaceum YK 391 was purified to apparent homogeneity with 272.9-fold purification with an overall yield of $13.8\%$. The enzyme consisted of dimeric polypeptides of 63 kDa, and the total molecular mass was calculated to be approximately 126 kDa. Besides cytosine, the enzyme deaminated 5-fluorocytosine, cytidine, 6-azacytosine, and 5-methylcytosine, but not 5-azacytosine. Optimum pH and temperature for the enzyme reaction were 7.5 and $30^{\circ}C$, respectively. The enzyme was stable at pH 6.0 to 8.0, and at 30T for a week. About $70\%$ of the enzyme activity was retained at $60^{\circ}C$ for 5 min. The apparent $K_{m}$ values for cytosine, 5-fluorocytosine, and 5-methylcytosine were calculated to be 0.38 mM, 0.87 mM, and 2.32 mM, respectively. The enzyme activity was strongly inhibited by 1 mM $Hg^{2+},\;Zn^{2+},\;Cu^{2+},\;Pb^{2+},\;and\;Fe^{3+}$, and by o-phenanthroline, $\alpha,\;{\alpha}'$-dipyridyl, p-choromercuribenzoate, N-bromosuccinimide, and cWoramine­T. In addition, the enzyme activity was strongly inhibited by I mM 2-thiouracil, and weakly inhibited by 2-thiocytosine, or 5-azacytosine. Finally, intracellular and extracellular cytosine deaminases from Chromobacterium violaceum YK 391 were found to have a different optimum temperature, apparent $K_{m}$ value, and molecular mass.

• Applied Biological Chemistry
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• v.35 no.6
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• pp.479-484
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• 1992

This study was undertaken to determine the effects of cultural conditions on cell growth and casein hydrolysis for cell production in order to add Micrococcus sp. LL3 as a potential agent for industrial application with aim of shortening ripening period and improving flavor. Optimum temperature for cell growth and caseinolysis was $30^{\circ}C$ and $37{\circ}C$, respectively, and optimum pH was 7.0. The enzyme remained stable up to $50^{\circ}C$. Hydrolysis patterns of casein were also observed on SDS-PAGE. Both ${\alpha}-casein$ and ${\beta}-casein$ were totally hydrolysed by enzymes from Micrococcus sp. LL3 during culture. A preferential attack on ${\beta}-casein$ was observed. Production of aminopeptidase which cleaved polypeptides was the highest in early stationary phase during cell growth.

• Fisheries and Aquatic Sciences
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• v.15 no.4
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• pp.283-291
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• 2012

This study examines the optimal fractionation method and conditions for the isolation of endoprotease- and exopeptidase-active fractions from crude extracts of cuttlefish hepatopancreas (HP) using four fractionation methods: ammonium sulfate fractionation (ASF), polyethylene glycol fractionation (PGF), ion exchange chromatography (IEC), and gel filtration chromatography (GFC). Total endoprotease activity highest in the fraction II (concentrate of fractions 34-42; 842.60 U) of GFC, followed by fraction III (40-60% ammonium sulfate fraction; 670.25 U) of ASF, fraction I (concentrate of fractions 8-12; 436.89 U) of IEC, and fraction II (10-20% polyethylene glycol; 307.31 U) of PGF. Total exopeptidase activity of these fractions was highest in fraction II (2,704.70 U) of GFC, fraction III (2,110.50 U) of ASF, fraction III (1,605.60 U) of PGF, and fraction II (concentrate of fractions 38-44; 1,196.22 U) of IEC. These results showed that fraction II of GFC had the highest activity toward both exopeptidase and endoprotease, with exopeptidase activity being 3.21 times higher than of endoprotease. These results suggest cuttlefish HP could be used as a potential source for the extraction of exopeptidase, an enzyme capable of catalyzing the cleavage of N- and C-terminal amino acids in polypeptides, Like endoprotease, the most efficient method for separating exopeptide-active fractions was GFC.

• YAKHAK HOEJI
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• v.41 no.3
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• pp.381-388
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• 1997

Metabolism of DWP401, recombinant juman epidermal growth factor, was examined in vivo and in vitro in rats. When $^{125}I$-labeled DWP401 was administered at a dose of 50 ${\mu}g$/kg by i.v. injection. $^{125}I$-labeled DWP401 was rapidly degraded within 30 minytes above 93%. Thin layer chromatography analysis of urine collected for 24 hr after i.v. administration of $^{125}I$-labeled DWP401 showed ohly one spot on a X-ray film which was considered as diiodo-tyrosine. This result suggests tha $^{125}I$-labeled DWP401 was completely digested into free amino acids without any specific intermediate polypeptides. About 42.1% of the administered iodine was recovered in 24 hr. For in vitro degradation study, $^{125}I$-labeled DWP401 was added to plama and tissue homogenates of rats and incubated at $37^{\circ}C$. Almost 98% of the added radioactivity recovered from the protein fraction of the liver, kidey, small intestine, stomach and spleen decreased rapidly. For examplem the recovery rates of $^{125}I$-labeled DWP401 were 58.6, 63.2, 39.9, 52.9 and 66.8% after 4hrs of incubation in respective organ homogenates.

• Korean Journal of Veterinary Research
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• v.26 no.1
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• pp.97-102
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• 1986

The prevalence of diarrhea caused by enterotoxigenic Escherichia coli was surveyed on 445 calves in 6 farms which were located in the central part of Korea. The incidence of enterotoxigenic Escherichia coli in calves with diarrhea was investigated by detecting the K99 and F41 antigens from the isolated strains of Escherichia coli The incidence of colibacillosis in calves was 23.3%. Of 238 strains of Escherichia coli isolated from calves with diarrhea, 73 strains(30.6%) were proved possessing the K99 antigen by mannose-resistant hemagglutination(MRHA) using horse red blood cells and 79(33.1%) possessing F41 antigens by MRHA using guinea-pig red blood cells. The minca medium, nutrient broth, tryptic soy broth and brain heart infusion were tested for yield of K99 and F41 pili. The production of pili was greatest in minea medium. The best detachment method of the K99 and F41 pili from the cells was heat treatment for 20 minutes at $60^{\circ}C$ and concentration by precipitation with ammonium sulfate. The purified antigens of K99 and F41 were polypeptides with molecular weights of 18,500 and 29,500, respectively by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.