• Korean Journal of Food Science and Technology
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• v.22 no.4
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• pp.466-472
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• 1990

The effect of sugar addition and heat treatment on the myofibrillar protein extractability was studied. Maillard reaction was dependent on heating time significantly and glucose revealed the highest reactivity for Maillard reaction. The extractability of myofibrillar proteins was lowest in case of glucose addition and decreased according to increasing of heating time, Higher extractability was resulted in by digestion of myofibrillar proteins with enzymes after sugar addition and heat treatment than the undigested samples, as the sample was digested with trypsin that is the highest. And by digestion with trypsin, chymotrypsin and peptidase at a time the extractability of meat proteins increased remarkably.

• BMB Reports
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• v.32 no.6
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• pp.573-578
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• 1999

Treatment of Hafnia alvei aspartase with limited tryptic digestion resulted in a marked increase in enzymatic activity. The activation required a few minutes to attain maximum level and, thereafter, the activity gradually decreased to complete inactivation. The degree of cleavage associated with the activation was extremely small as judged by SDS-PAGE. Upon activation, the optimum pH and temperature were essentially unchanged. When trypsin-activated enzyme was denatured in 4 M guanidine-HCI followed by removal of the denaturant by dilution, the restoration of activity was similar (40%) to that of the native enzyme, indicating a degree of stability. The $pK_a$ obtained on the acidic side and the $pK_b$ obtained on the basic side of trypsin-activated aspartase were 6.6 and 8.6, respectively, the same as those of the native aspartase, indicating that aspartase may exist in a stable conformation after limited tryptic digestion. These results indicate that the activation of H. alvei may be mediated by a conformational change away from the active site of individual subunits.

• Mass Spectrometry Letters
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• v.7 no.1
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• pp.1-11
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• 2016

Various efforts have been developed to improve sample preparation steps, which strongly depend on hands-on processes for accurate and sensitive quantitative proteome analysis. In this study, we carried out heating the sample prior to trypsin digestion using an instrument to improve the tryptic digestion process. The heat shock generated by the system efficiently denatured proteins in the sample and increased the reproducibility in quantitative proteomics based on peptide abundance measurements. To demonstrate the effectiveness of the protocol, three cell lines (A human lung cancer cell line (A549), a human embryonic kidney cell line (HEK293T), and a human colorectal cancer cell line (HCT-116)) were selected and the effect of heat shock was compared to that of normal tryptic digestion processes. The tryptic digests were desalted and analysed by LC-MS/MS, the results showed 57 and 36% increase in the number of identified unique peptides and proteins, respectively, than conventional digestion. Heat shock treated samples showed higher numbers of shorter peptides and peptides with low inter-sample variation among triplicate runs. Quantitative LC-MS/MS analysis of heat shock treated sample yielded peptides with smaller relative error percentage for the triplicate run when the peak areas were compared. Exposure of heat-shock to proteomic samples prior to proteolysis in conventional digestion process can increase the digestion efficiency of trypsin resulting in production of increased number of peptides eventually leading to higher proteome coverage.

• Preventive Nutrition and Food Science
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• v.4 no.2
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• pp.145-151
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• 1999

Apolipoprotein B-100 (apo B-100) is an important component in plasma low density lipoproteins (LDL). It function as the ligand for the LDL receptor in peripheral cells. The LDLs are removed from the circulation by both high-affinity receptor-mediated and receptor-independant pathways. LDLs are heterogeneous in their lipid content, size and density and certain LDL subspecies increase risk of atherosclerosis due to differences in the conformation of apo B in the particle. In the present study , surface and core peptide fraction of Apo B-100 have been characterized by comparing peptide-mapping and fluorescence spectroscopy. Surface fragments of apo B-100 were generated by digestion of LDL with either trypsin , pronase, or pancreatin elastase. Surface fractions were fractionated on a Sephadex G-50 column. The remaining core fragments were delipidated and redigested with the above enzymes, and the resulting core peptides were compared with surface peptides. Results from peptide-mapping by HPLC showed pronase-digestion was more extensive than trypsin -digestion to remove surface peptide fraction from LDL. Fluorescence spectra showed that core fractions contained higher amount of tryptophan than surface fractions, and it indicated that core fraction wa smore hydrophobic than surface fractions. A comparison of the behavior of the core and surface provided informations about the regions of apo B-100 involved in LDL metabolism and also about the structural features concerning the formation of atherosclerosis.

• Proceedings of the Zoological Society Korea Conference
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• 2001.10a
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• pp.216.2-217
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• 2001

No Abstract, See Full Text

• Analytical Science and Technology
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• v.30 no.2
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• pp.96-101
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• 2017

This study investigated the effect of centrifugation on tryptic digestion. This was done by applying different centrifugation speeds (6,000, 8,000, 10,000, 20,000, and $30,000{\times}g$) over various durations (0, 10, 20, 30, 40, 50, and 60 min) to digest two model proteins - cytochrome c and myoglobin. The intact proteins and resulting peptides were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Centrifugation greatly improved the tryptic digestion efficiency of cytochrome c, where either an increase in centrifugation speed or in digestion duration significantly improved the digestion of cytochrome c. However, centrifugation did not noticeably improve the digestion of myoglobin; 16 h of centrifuge-assisted tryptic digestion at $30,000{\times}g$ barely removed the myoglobin protein peak. Similar results were also obtained when using conventional tryptic digestion with gentle mixing. When acetonitrile (ACN) was added to make 10% ACN buffer solutions, the myoglobin protein peak disappeared after 6 h of digestion using both centrifuge-assisted and conventional tryptic digestions.

• Korean Journal of Veterinary Research
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• v.28 no.1
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• pp.155-163
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• 1988

For the laboratory diagnosis of Sarcocystis infections especially in domesticated food animals, several antificial digestion techniques were applied for the musculature specimens and several staining techniques was applied for the bradyzoites of Sarcocystis species isolated. The digestion technique using trypsin(0.5%) and sodium chloride(0.85%) mixed solution was regarded as the most valuable for the detection of asexual stages of Sarcocystis in bovine musculature specimens. Optimal time for digestion was approximately one to four hours. The trypsion digestion technique with Giemsa's stain could be helpful for the detection of Sarcocystis prolferative forms and for the observation of the nucleus of the parasite. A systematic detection was also performed in an autopsy for a bovine carcass naturally infected with Sarcocystis species, and the asexual stages such as metrocytes and bradyzoites were observed in the specific organs, respectively.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.3
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• pp.149-158
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• 2005

This paper describes design, fabrication, and application of the silicon based temperature controllable micro reactor. In order to achieve fast temperature variation and low energy consumption, reaction chamber of the micro reactor was thermally isolated by etching the highly conductive silicon around the reaction chamber. Compared with the model not having thermally isolated structure, the thermally isolated micro reactor showed enhanced thermal performances such as fast temperature variation and low energy consumption. The performance enhancements of the micro reactor due to etched holes were verified by thermal experiment and numerical analysis. Regarding to 42 percents reduction of the thermal mass achieved by the etched holes, approximately 4 times faster thermal variation and 5 times smaller energy consumption were acquired. The total size of the fabricated micro reactor was $37{\times}30{\times}1mm^{3}$. Microchannel and reaction chamber were formed on the silicon substrate. The openings of channel and chamber were covered by the glass substrate. The Pt electrodes for heater and sensor are fabricated on the backside of silicon substrate below the reaction chamber. The dimension of channel cross section was $200{\times}100{\mu}m^{2}$. The volume of reaction chamber was $4{\mu}l$. The temperature of the micro reactor was controlled and measured simultaneously with NI DAQ PCI-MIO-16E-l board and LabVIEW program. Finally, the fabricated micro reactor and the temperature control system were applied to the thermal denaturation and the trypsin digestion of protein. BSA(bovine serum albumin) was chosen for the test sample. It was successfully shown that BSA was successfully denatured at $75^{\circ}C$ for 1 min and digested by trypsin at $37^{\circ}C$ for 10 min.

• BMB Reports
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• v.32 no.6
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• pp.567-572
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• 1999

We have previously shown that a DNA fragment is responsible for the anticoagulatory effect of an earthworm, Lumbricus rubellus. The anticoagluant increased the activated partial thromboplastin time (APTT) and also inhibited the thrombin activity observed with either N-${\alpha}$-p-tosyl-L-arginine methyl ester (TAME) or H-D-phenyl-alanyl-L-pipecoil-L-arginine-p-nitroanilide (S-2238). Since trypsin digestion of the anticoagulant further increased the APTT, the possible presence of a regulatory protein for the anticoagulatory DNA was investigated by digesting the anticoagulant with trypsin and isolating the DNA fragment with C4-reversed phase HPLC. The DNA fragment lacking a regulatory protein was eluted in the flow-through fraction, and analyzed with thrombin and activated factor X. Activated factor X activity was more strongly inhibited than thrombin activity. For DNA digestion, we treated the anticoagulant with DNase and purified the DNA-binding protein with a FPLC Resource-S cation exchange column. The regulatory protein, with an $M_r$ of 55.0 kDa, reduced the anticoagulatory effect of the DNA fragment.

• International Journal of Industrial Entomology and Biomaterials
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• v.25 no.2
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• pp.187-193
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• 2012

Serine proteases are major insect enzymes involved in the digestion of dietary proteins and in the process of blood meal digestion. In this study, cDNA was constructed using the whole body of Laccotrephes japonensis. The flanking sequences of the 5- and 3- end of this gene were characterized by RACE-PCR. Sequence analysis showed that this gene contained a 963-bp ORF encoding 320 amino acids. The deduced amino acid sequence showed 62% identity with the Creontiades dilutus serine protease, 58% with the Lygus lineolaris trypsin precursor, and 54% with the Triatoma infestans salivary trypsin. To assess the expression of the L. japonensis serine protease (JGsp), the JGsp gene was cloned into a baculovirus transfer vector, pBac-1, and expressed in Sf9 cells (Spodoptera frugiperda). SDS-PAGE and western blot analysis have shown that the JGsp recombinant protein was a monomer with a molecular weight of about 32 kDa. Recombinant JGsp has shown activity in the protease enzyme assay using gelatin as a substrate.