• Journal of Sericultural and Entomological Science
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• v.35 no.1
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• pp.60-68
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• 1993

It has been known that the silk degumming treated by hot alkali solution is easy to handle but is liable to yield poor-quality silk due to the degree of degumming loss, incomplete-degumming or over-degumming. Therefore, many studies have been carried out on the silk degumming by enzyme in order to improve the quality of silk. However, no attention has been paid to the physicochemical analysis of enzymatic degummed silk. In this paper, two different degumming methods, soap and enzymatic, are compared in aqueous solution state of silk fibroin. The results can be summarized as follows: There was no significant difference between two solutions on the bases of polarizing microscopy, TEM observation and SDS-PAGE. Spherulite of silk fibroin was not observed in polarizing microscopy, however the leaf-shape fibril structure was developed upon solidification. The size of spherulites of silk fibroin in TEM observation were 30~120nm with a wide range of size distribution. The intrinsic viscosity of enzymatic degummed fibroin solution was lower than that of soap degummed solution. This can be explained that the silk fibroin was more degraded by enzymatic degumming method compared with the soap degumming method. SDS-polyacrylamide gel electrophoresis showed that the fibroin molecule was composed of large component of molecule weight above 50 kd and small component of molecule weight about 20 kd. There was no difference in crystallinity between two degumming methods on the bases of results of DSC thermograms and IR spectra.

• Applied Biological Chemistry
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• v.19 no.3
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• pp.162-171
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• 1976

The determination of rate limiting step in the metabolic process is of great importance to understand the metabolic properties. In this paper the authors propose a modified enzymatic method instead of thermodynamic method. This method is based on the assumption that the over-all rate increment would be larger than by any other steps to which the individual enzyme are added respectively, provided that the enzyme participated in the rate limiting step is added to the reactions composed of n steps of metabolic process with which n kind of enymes are concerned. The present paper deals with analysis and discussion about some factors having influence on the proposed process, mainly about the metabolic process constituted with homogeneous steps. The results show that the determination of rate limiting step by a modified enzymatic method is feasible, provided that some restrictions are added in any type of mechanisms.

• Applied Biological Chemistry
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• v.40 no.3
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• pp.220-224
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• 1997

As corn starches with different amylose content were heated at different temperature $(100^{\circ}C,\;121^{\circ}C)$ with starch / water ratio (1:3.5, 1:9) and heating-cooling treatment was repeated up to 4 times, the yield of RS(resistant starch) from heated corn starches was investigated by the enzymatic-gravimetric method and the ${\alpha}-amylase$ treatment. Compared to ${\alpha}-amylase$ method, enzymatic-gravimetric method was more effective to hydrolyze the amorphous region of heated corn starch. With increasing the amylose content and the number of heating-cooling treatment, the yield of RS increased, regardless of isolation method. Heated corn starches formed at $121^{\circ}C$ provided higher yield of RS than those formed at $100^{\circ}C$. Higher RS yield was also observed in the case of starch/water ratio (1:3.5) compared to the case of ratio (1:9).

• Preventive Nutrition and Food Science
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• v.14 no.4
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• pp.323-328
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• 2009

Cryotin F could be used for hydrolyzing shrimp byproducts into bioactive ingredients, which could be used as value-added products. The objective of this study was to investigate the optimum condition for antioxidative activities of the enzymatic hydrolysate produced with Cryotin F using response surface methodology with central composite rotatable design. Shrimp byproducts (shells and heads) were hydrolyzed with Cryotin F. The experimental ranges of the independent variables for 20 experimental runs were 28.2-61.8${^{\circ}C}$ reaction temperature, pH 6-10 and 0.5-5.5% enzyme concentration. The degree of hydrolysis for the reaction products was measured. Their antioxidative activities were measured using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging activity and Fe-chelating activity. The experimental method with central composite rotatable design was well designed to investigate the optimum condition for biofunctional ingredients with antioxidative activities using Cryotin F because of their high R2 values of 0.97 and 0.95 for DPPH-scavenging activity and Fe-chelating activity, respectively. Change in enzyme concentration did not significantly affect their antioxidative activities (p<0.05). Both DPPH scavenging activity and chelating activity against Fe for the enzyme hydrolysates were more affected by the pH of enzyme hydrolysis than by their action temperature. DPPH-scavenging activity was higher at acidic pH than alkali pH, while chelating activity against Few was inversely affected. Hydrolysate of shrimp byproducts showed high antioxidative activities depending on the treatment condition, so the optimum treatment of enzymatic hydrolysate with Cryotin F and other proteases can be applied to shrimp byproducts (shells) and other protein sources for biofunctional ingredients.

• Applied Biological Chemistry
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• v.50 no.4
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• pp.304-307
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• 2007

An efficient production method of spirulina extract was developed by enzymatic treatment using cell lytic and proteolytic enzymes. The suitable dosage of Tunicase, a cell lytic enzyme, was found to be 2.0% (w/w). Proteolytic enzymes were screened to obtain high solid recovery and spirulina extraction (SE) index, which indicates nucleic acid-related substances content. Among the seven tested proteases, Esperase was selected and optimal dosage of this enzyme was 2.0% (w/w). The solid recovery and SE index of simultaneous treatment and co-treatment using optimal dosages of Tunicase and Esperase were greatly similar, respectively. However, co-treatment had the effect of shortening total hydrolysis time. The SE index and solid recovery of co-treatment were significantly enhanced by 75% $(11.4{\rightarrow}20.0)$ and 45% $(45.2%{\rightarrow}65.3%)$, respectively, than those of the non-treated extracts.

• Analytical Science and Technology
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• v.7 no.2
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• pp.245-251
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• 1994

In order to determine sodium chondroitin sulfate in the mixture, chondroitinase ABC was used for enzymatic reaction. The procedure was rapid, simple, quantitative and the HPLC analysis of ${\Delta}Di-6S$(2-actamido-2-deoxy-3-0-(${\beta}$-D-gluco-4-enepyranosyluronic acid)-6-0-sulfo-D-galactose) in the sodium chondroitin sulfate was obtained. The absorbance was measured at 230nm and detection limit was $1{\mu}g/ml$. When we applied this method to the drugs(capsule, opthalmic solution), it gave the mean contents of $100.01{\pm}1.58%$ and $99.89{\pm}1.80%$ respectively.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.430-435
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• 2014

Physical and chemical barriers, caused by the close association of the main components of cellulosic biomass, hinder the hydrolysis of cellulose to fermentable sugars. Since the main goal of pretreatment is to increase the enzyme accessibility improving digestibility of cellulose, development of an effective pretreatment process has been considered to be important. In this study, SAA (Soaking in Aqueous Ammonia) was chosen as pretreatment because this is the simple and low-cost method. Rice straw of which the production is outstandingly high in domestic agriculture residues in Korea was chosen as raw material. SSA pretreatment with various reaction time of 3 h to 72 h was tested. The enzymatic hydrolysis and SSF (Simultaneous Saccharification and Fermentation) were performed at three different temperature (30, 40 and $50^{\circ}C$) to investigate performance of SSF upon various pretreatment conditions. As a result, this SAA treated-rice straw was found to have great potential for effective enzymatic hydrolysis and SSF with lower enzyme dosage at lower temperature ($30^{\circ}C$) than its conventional SSF. In SAA addition, SAA reduced fermentation time to 24 h owing to increase the initial hydrolysis rate substantially.

• Preventive Nutrition and Food Science
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• v.13 no.4
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• pp.313-320
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• 2008

Efficiency of a far-infrared radiation (FIR) dryer for drying of citrus by-products (CBPs) was evaluated through their antioxidant activities. The CBPs dried through FIR were enzymatically digested by six carbohydrases (AMG, Celluclast, Pectinase, Termamyl, Ultraflo and Viscozyme) to prepare digests for evaluation of the activities. The total polyphenolic and total flavonoid contents of the digests were determined by colorimetric assays. The AMG digest was selected for the further experiments. The antioxidant potential of the digests were evaluated by DPPH, superoxide, hydroxyl and alkyl radical scavenging activities, $H_2O_2$ scavenging activity, metal chelating, lipid peroxidation inhibition and the reduction of DNA damage. The AMG digest from CBPs dried through FIR at $50^{\circ}C$ showed strong antioxidant activities in DPPH, superoxide, hydrogen peroxide, alkyl and metal chelating assays while all the digests showed strong lipid peroxidation activities. Further, enzymatic digests showed remarkable inhibitory activities against $H_2O_2$-induced DNA damage. Hence, the data obtained using different in vitro models clearly established the antioxidant potential of enzymatic digests from CBPs dried through FIR. Furthermore, they can be used as a source of natural antioxidants; hence, far-infrared radiation drying is a viable method for transforming wet CBPs into a dried form without destroying the bioactive components.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.478-483
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• 1997

${\gamma}-Glutamylcysteine$ synthetase was purified from E. coli K-12 strain and its properties related to the in vitro synthesis of glutathione by enzymatic method were investigated. The activity of purified ${\gamma}-glutamylcysteine$ synthetase was increased with increasing concentration of L-glutamate up to 60 mM, while it was decreased by about 50% and 40% under 60 mM of L-cysteine and 45 mM of glycine, respectively. The enzyme activity was reduced not only by ADP, one of the reaction products, but also by the reduced form of glutathione. Therefore, because the reduced glutathione as well as glycine which is the substrate for glutathione synthetase inhibit the activity of ${\gamma}-glutamylcysteine$ synthetase, it is recommended to design a bioreactor system with two separate reactions for glutathione synthesis : one with ${\gamma}-glutamylcysteine$ synthetase reaction and the other glutathione synthetase reaction. In addition since ADP, resulted from these reactions, reduces the activity of ${\gamma}-glutamylcysteine$ synthetase, it is necessary to introduce an ATP regeneration system for glutathione synthesis.

• YAKHAK HOEJI
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• v.56 no.4
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• pp.222-229
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• 2012

In order to determine acetylcholine and choline in the biological samples, the specific enzymes of acetylcholinesterase (AChE) and choline oxidase (ChO), which utilize acetylcholine and choline as substrates, were employed to convert substrates to $H_2O_2$. The produced $H_2O_2$ was coupled to 4-aminoantipyrine/phenol with peroxidase (PO) yielding quinoneimine dye which was measured at 508 nm. In the present enzymatic spectrophotometric analysis the product at the equilibrium state was measured considering accuracy, precision, time and cost of the analysis. The developed analytical method yielded good linearity (calibration curve; $A_{508}$=9534[acetylcholine]+0.009, correlation coefficient ($R^2$); 0.999) with detection limit of $1.11{\times}10^{-7}M$, reasonable precision (relative standard deviation; 0.10~1.62% at $2.5{\times}10^{-6}M{\sim}1.25{\times}10^{-4}M$) and accuracy (relative error; -0.24~0.97% at $4.13{\times}10^{-6}M{\sim}1.01{\times}10^{-4}M$) for acetylcholine chloride standard solution. The concentrations of acetylcholine and choline in human serum were found as $3.20{\times}10^{-5}M$ and $1.14{\times}10^{-4}M$, respectively. The brain tissues of Sprague-Dawley strain rat contained 9.82${\mu}g/g$ of acetylcholine and 6.53 ${\mu}g/g$ of choline in the cerebrum, while 7.37 ${\mu}g/g$ of acetylcholine and 5.34 ${\mu}g/g$ of choline in the cerebellum.