• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.85-88
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• 2002

A study was carried out on the application of supercritical fluid to the hydrolysis of boll fibers of cotton (cultivar Tashkent-6 of Gossypium hirsutum L.) by cellulase enzymes from Trichoderma viride, Trichoderma reesei and Aspergillus niger. Conditions of the enzymatic process were optimized. The stabilities of cellulase enzymes were sustained at the pressure of up to 160 attn for 48 hours at 5$0^{\circ}C$ in supercritical carbon dioxide.

• Food Science and Biotechnology
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• v.16 no.3
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• pp.381-385
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• 2007

The objective of this experiment was to study the influence of feed moisture content on the degree of enzymatic hydrolysis of com starch in a twin screw extruder and the saccharification yield of the dried extrudate. The feed moisture content was set at 25, 30, and 35% and ${\alpha}$-amylase solution was directly injected into the feed section at a barrel temperature of $95^{\circ}C$ and screw speed of 250 rpm. Amyloglucosidase was used for the saccharification of the dried extrudate at a concentration of 0.055%(w/w). Expansion ratio and swelling factor of extrudates decreased with increasing the feed moisture content. Addition of ${\alpha}$-amylase during extrusion process raised reducing sugar content of extrudates which also increased with the feed moisture content. The saccharification yield of dried extrudate was higher for the extrudate with lower feed moisture content.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.35-39
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• 1998

An enzymatic process was developed to produce protein hydrolysater form defatted soya protein. Various unit operations were tried, and the effects of pre- and post-treatments on the product characteristics such as degree of hydroylsis (DH), free amino acid content (%FAA) and average molecular weight (MW) were investigated. The use of acid washes showed no difference in %DH. Increasing pH during pre-cooking gave lower %DH. Alkaline cooking made too much insoluble protein, thus the protein yield was too small. A better hydrolysis with more acceptable taste was obtained when the combination of Neutrase/Alcalase/Flavourzyme was used in place of Alcalase/Flavourzyme combination; Untoasted defatted soya was more effective on the proteolysis than toasted one. The MW of the evaporated and spray dried product was higher than that of undried product, due to precipitation of low-solubility components. When ultrafiltration and the product concentration carried out the product separation by reverse osmosis, the solubility and the taste of the product were improved. The difference between enzyme hydrolysate and acid hydrolysate was significant in free amino acid composition, especially in tyrosine, phenylalanine, glutamine and asparagine.

• Journal of Adhesion and Interface
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• v.7 no.2
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• pp.19-25
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• 2006

Since the enzymatic degradation of microbial poly(hydroxylalkanoate)s (PHAs), such as poly[(R)-3-hydroxybutyrate] and poly[(R)-3-hydroxybutyrate-co-3-hydroxyvalerate] initially occurs by a surface erosion process, their degradation behaviors can be controlled by the change of surface property. In order to control the rate of enzymatic degradation, plasma modification technique was applied to change the surface property of microbial PHAs. The surface hydrophobic and hydrophilic properties of PHA films were introduced by $CF_3H$ and $O_2$ plasma exposures, respectively. The enzymatic degradation was carried out at $37^{\circ}C$ in 0.1 M potassium phosphate buffer (pH 7.4) in the presence of an extracellular PHB depolymerase purified from Alcaligenes facalis T1. The results showed that the significant retardation of initial enzymatic erosion of $CF_3H$ plasma-treated PHAs was observed due to the hydrophobicity and the enzyme inactivity of the fluorinated surface layers while the erosion rate of $O_2$ plasma-treated PHAs was not accelerated.

• BMB Reports
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• v.37 no.3
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• pp.339-342
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• 2004

Germination is a process which characterized with nescient synthesis of genes. Among the genes synthesized during the germination of wheat embryos, germin genes, proteins and their enzymatic activity were defined. Germin is a water soluble homopentameric glycoprotein which is remarkable resistant to degradation by a broad range of proteases including pepsin. Germin proteins found to have strong oxalate oxidase activity which produces hydrogen peroxide by degrading oxalic acid. The current study, aimed to localize the germin genes, proteins and enzymatic activities in developing coleoptiles which is a rapidly growing protective tissue of leaf primordium and shoot apex. Non-radioactively abeled germin riboprobes were employed to localize germin mRNAs in situ. FITC (Fluorescein isothiocyanate) and alkaline phosphatase linked anti-germin antibodies were used to localize germin proteins under the fluorescence and light microscopy and finally germin enzymatic activity was localized by using appropriate enzyme assay. The results revealed that in coleoptiles germin genes, proteins and their enzymatic activity were predominantly associated with the cells of epidermis and vascular bundle sheath cells.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.1
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• pp.7-13
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• 2001

Enzymatic hydrolysis of different forms of silk fibroin (soluble, gel and insoluble forms) by industrial and commercial enzyme preparations to obtain aqueous and powdered silk fibroin in relatively mild conditions was investigated. A mono-enzymatic hydrolysate systems were tested for hydrolysis of water-soluble form of fibroin as most productive form of protein substrate. Insoluble forms of substrate usually were hydrolyzed less effective. In some cases from soluble fibroin substrate gel was formed during hydrolysis process. This hindered intermixing and decreased rates of hydrolysis. Insoluble sediments were formed in enzymatic hydrolysates in other cases. These sediments and also sediment after chemical hydrolysis were purified and tested on amino acids content for comparison. Sediments formation in these conditions are considered as pure tyrosine isolation method. Obtained hydrolysates were characterized by gel-chromatography analysis and other standard biochemical methods. Possibility of application of enzymatic hydrolysis for preparation of silk fibroin hydrolysates is discussed.

• BMB Reports
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• v.40 no.6
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• pp.888-894
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• 2007

Src homology (SH) domains of phospholipase C-$\gamma1$ (PLC-$\gamma1$) impair NGF-mediated PC12 cells differentiation. However, whether the enzymatic activity is also implicated in this process remains elusive. Here, we report that the enzymatic activity of phospholipase C-$\gamma1$ (PLC-$\gamma1$) is at least partially involved to the blockage of neuronal differentiation via an abrogation of MAPK activation, as well as sustained Akt activation. By contrast, Overexpression of WT-PLC-$\gamma1$ exhibited sustained NGF-induced MAPK activation, and triggered transient Akt activation resulting in profound inhibition of neurite outgrowth. However, lipase-inactive mutant (LIM) PLC-$\gamma1$ cells fail to suppress neurite outgrowth, although it contains intact SH domains, specifically enhancing the expression of cyclin D1 and p21 proteins, which regulate the function of retinoblastoma Rb protein. These observations show that the lipase inactive mutant of PLC-$\gamma1$ does not alter NGF-induced neuronal differentiation via enzymatic inability and the modulation of cell cycle regulatory proteins independent on SH3 domain.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.163-167
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• 2006

Pectin was enzymatically extracted from industrial lemon pomace by using an endo-polygalacturonase from Aspergillus niger as a processing aid and compared to pectin extraction by hot hydrochloric acid. The yield of pectin was 17.6 and 20.2% with enzymatic and acidic treatments, respectively. The molecular weight distribution did not vary greatly between the samples extracted with enzyme or acid. Large differences in charge density were observed, however, when the samples were analyzed by anionic-exchange chromatography. Pectin extracted by the enzymatic treatment indicated higher charge density than that obtained by hydrochloric acid. The higher charge density could due to the presence of endogenous lemon pectinesterase, which was activated at low pH 4.5 in situ conditions during the process of enzymatic extraction, leading to low methoxylated pectin with a higher charge density.

• Journal of Sericultural and Entomological Science
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• v.35 no.1
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• pp.52-59
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• 1993

Raw silk degumming, by which the sericin and other marterials are eliminated from fibroin, is very essential process to produce silk fabrics. Alkali chemicals and enzymes have been used for the silk-degumming process. In this paper, the effect of heat treatment was investigated on silk fibers degummed by two different methods, soap and enzymatic degumming method. The difference between these two degumming methods was analyzed on the basis of results of mechanical testing, thermal analysis and intrated spectroscopy. The tenacity and the elongation of silk fiber are decreased by the heat-treatment in wet state. This tendency is observed in both cases of two degumming methods. The peak temperature in DSC analysis, which is attributed to thermal decomposition of silk fiber, was shifted to higher value with the heat-treatment temperature for the soap degummed silk fiber, however, it was not for the enzymatic degummed one. The IR crystallinity of soap digummed silk fiber is increased with the heat-treatment temperature, while that of enzymatic degummed fiber is not.

• Journal of Sericultural and Entomological Science
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• v.34 no.2
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• pp.41-51
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• 1992

In this thesis, both soap and enzymatic degumming method were adopted and the optimum degumming conditions were obtained. Difference between the two degumming methods in silk fiber state was investigated and analyzed on the basis of the results of physical testings, polarizing microscopy, scanning electron microscopy, viscosity measurement, (${\alpha}$＋$\varepsilon$) amino group contents measurement, birefringence measurement, amino acid analysis, thermal analysis, infrared spectroscopy and x-ray diffraction analysis. The results obtained were summarized as follows; Physical test results of the degummed silk fiber showed that the tenacity and the elongation of enzymatic degummed silk fiber were lower than those of soap degummed fiber. But SEM observation and amino acid analysis showed almost the same tendency in the two degumming methods. The viscosity of enzymatic degummed silk fiber was lower than that of soap degummed fiber, but (${\alpha}$＋$\varepsilon$) amino group contents was higher in the enzymatic degummed fiber. It can be suggested that the enzymatic degummed silk fibroin was more degraded than the soap degummed fibroin. The birefringence, endothermic temperature of DSC spectrum, IR crystallinity and X-ray lateral order factor of enzymatic degummed silk fiber were higher than those of soap degummed fiber. It seems that the enzymatic degummed silk fiber has the higher crystallinity than that of soap degummed one according to the above results. However, it can be inferred that these differences between soap and enzymatic degummed fiber would be lessened if pretreatment and aftertreatment were included in the enzymatic degumming process.