• BMB Reports
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• 제28권1호
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• pp.79-82
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• 1995

Exposure of spleen lymphocytes to 2-chloroethylethyl sulfide (CEES) leads to a reduction of the intracellular ATP level, followed by a decrease in cell viability. Addition of nicotinamide, an inhibitor of poly(ADP-ribose) polymerase (PADPRP), restores both ATP level and viability, indicating that an activation of PADPRP is responsible for the cytotoxicity of CEES. The involvement of a $Ca^{2+}$-mediated process in cytotoxicity is suggested. Verapamil, EGTA, trifluoperazine, and butacaine exhibit a partial protection (20 to 58%) against the cytotoxicity of CEES. Investigation of the causative role of proteolytic degradation in cell death indicate that pepstatin and leupeptin exert a substantial protective effect (60 to 70%), suggesting the involvement of lysosomal destabilization in CEES-induced cytotoxicity. Also, lysosomotropic agents markedly decrease the cytotoxicity. Lysosomal labilization may be a mechanism for the cytotoxicity of CEES.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2006년도 Spring Conference
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• pp.77-90
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• 2006

Beta-amyloid peptide (A$\beta$) is a major component of senile plaques and its aggregation is considered to play a critical role in pathogenesis of Alzheimer's disease (AD). Aggregation of A$\beta$ could result from both increased synthesis and decreased degradation of A$\beta$. Our laboratory is interested in understanding the mechanism of A$\beta$ degradation in brain. Recently our laboratory identified a bacterial gene (SKAP) from Streptomyces sp KK565 whose protein product has an activity to cleave A$\beta$ and thus reduce the A$\beta$-induced neurotoxicity. The sequence analysis showed that this gene was closely related to aminopeptidase. Maldi-Tof analysis showed that the recombinant SKAP protein expressed in E. coli cleaves both A$\beta$ 40 and A$\beta$ 42 at the N-terminal of A$\beta$ while an aminopeptidase from Streptomyces griseus (SGAP) cleaves at the C-terminal. We also identified a mammalian homolog of SKAP and the recombinant mammalian protein expressed in Sf-9 insect cells showed a similar proteolytic activity to SGAP, cutting A$\beta$ at the C-terminus. I well discuss the detailed mechanism of the enzyme action and its functional implication in AD.

• Asian-Australasian Journal of Animal Sciences
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• 제26권3호
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• pp.443-454
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• 2013

Tenderness is the most important meat quality trait, which is determined by intracellular environment and extracellular matrix. Particularly, specific protein degradation and protein modification can disrupt the architecture and integrity of muscle cells so that improves the meat tenderness. Endogenous proteolytic systems are responsible for modifying proteinases as well as the meat tenderization. Abundant evidence has testified that calpains (CAPNs) including calpain I (CAPN1) and calpastatin (CAST) have the closest relationship with tenderness in livestock. They are involved in a wide range of physiological processes including muscle growth and differentiation, pathological conditions and post-mortem meat aging. Whereas, Calpain3 (CAPN3) has been established as an important activating enzyme specifically expressed in livestock's skeletal muscle, but its role in domestic animals meat tenderization remains controversial. In this review, we summarize the role of CAPN1, calpain II (CAPN2) and CAST in post-mortem meat tenderization, and analyse the relationship between CAPN3 and tenderness in domestic animals. Besides, the possible mechanism affecting post-mortem meat aging and improving meat tenderization, and current possible causes responsible for divergence (whether CAPN3 contributes to animal meat tenderization or not) are inferred. Only the possible mechanism of CAPN3 in meat tenderization has been confirmed, while its exact role still needs to be studied further.

• Journal of Animal Science and Technology
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• 제65권6호
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• pp.1151-1168
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• 2023

Tenderness and taste characteristics of meat are the key determinants of the meat choices of consumers. This review summarizes the contemporary research on the molecular mechanisms by which postmortem aging of meat improves the tenderness and taste characteristics. The fundamental mechanism by which postmortem aging improves the tenderness of meat involves the operation of the calpain system due to apoptosis, resulting in proteolytic enzyme-induced degradation of cytoskeletal myofibrillar proteins. The improvement of taste characteristics by postmortem aging is mainly explained by the increase in the content of taste-related peptides, free amino acids, and nucleotides produced by increased hydrolysis activity. This review improves our understanding of the published research on tenderness and taste characteristics of meat and provides insights to improve these attributes of meat through postmortem aging.

• 한국축산식품학회지
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• 제20권1호
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• pp.8-14
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• 2000

In order to examine physicochemical gelation behavior of ultra high temperature(UHT) pasteurized milk during storage at 4$^{\circ}C$ and 25$^{\circ}C$, pH, electrophoresis, alcohol test, sialic acid contents and free amino groups contents were biweekly determined. The pH of UHT pasteurized milk decreased with increasing storage time. Gelation of the UHT milk occured faster at 25$^{\circ}C$ than at 4$^{\circ}C$ with larger decreasing rate of pH. The alcohol test showed positive results at lower pH than 6.5, which could indicate the casein instability and beginning of gelation. The electrophoretic patterns showed a decrease in the concentrations of all caseins. Degradation of k-casein was faster in all cases, while $\alpha$-casein and $\beta$-casein were also extensively degraded later. The sialic acid contents of the samples increased gradually during storage, and the increasing rate was higher before gel formation. The free amino groups of the samples increased gradually during storage. The increasing rate of free amino groups was faster at 25$^{\circ}C$ than at 4$^{\circ}C$. The samples stored at 25$^{\circ}C$ gelled earlier than those stored at 25$^{\circ}C$, with corresponding increase of free amino groups. The residual proteolytic enzymes, which survived during the UHT heat treatments and were reactivated during storage, could be responsible for UHT pasteurized milk gelation during storage. It is assumed that proteolytic degradation of caseins followed by aggregation would be attributable to complicated reaction mechanism.

• Toxicological Research
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• 제19권2호
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• pp.91-98
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• 2003

Alkylating agents form alkylated base adducts in the DNA and cause DNA lesions leading to cell killing. In this study, we investigated the mechanism of apoptosis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in PC-3 and DU145 human prostate carcinoma cell lines. MNNG treatment resulted in the inhibition of cell proliferation in a concentration-dependent manner to a similar extent in both cell lines. This anti-proliferative effect of PC-3 and DU145 cells by MNNG was associated with morphological changed such as membrane shrinking, cell rounding up and formation of apoptotic bodies. MNNG treatment also induced a proteolytic cleavage of specific target proteins such as poly(ADP-ribose) polymerase (PARP) and $\beta$-catenin proteins in DU145 cells but in PC-3 cells. Furthermore, we observed an increase of proapoptotic protein Bax family expression and a decrease of antiapoptotic protein Bcl-2 family by MNNG treatment in a concentration-dependent manner MNNG also induced a proteolytic activation of caspase-3 and -9, which is believed to play a central role in the apoptotic signaling pathway.

• Asian-Australasian Journal of Animal Sciences
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• 제25권3호
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• pp.435-446
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• 2012

The present study identified volatile flavor components of Hanwoo longissimus muscle and other Korean foods (Doenjang, Chungukjang, sesame oil) and their traits were compared in relation with flavor precursors that include fatty acids and protein degradation products. Hanwoo longissimus muscle was purchased from a commercial abattoir while the other foods were sampled from three separate households. The results showed totals of 68 ($9.94{\mu}g/g$), 60 ($15.75{\mu}g/g$), 49 ($107.61{\mu}g/ml$) and 50 ($7.20{\mu}g/g$) volatile components for Doenjang, Chungukjang, sesame oil and Hanwoo beef longissimus, respectively (p<0.05). Aldehydes were the most predominant components in beef, but alcohols, acids and esters, and pyrazines are probably the major contributors to the flavor characteristics of other foods. SDS-PAGE revealed that beef longissimus muscle and Doenjang showed higher protein degradation than other foods which could be likely related to chiller ageing and ripening process. The total polyunsaturated fatty acids were approximately 50, 60, 41 and 5% for Doenjang, Chungukjang, sesame oil and beef longissimus muscle, respectively. Based on the mechanism(s) of generation of the volatile compounds and the chemical composition of each food sample, differences and traits of volatile flavor components among the four food types are likely due to fatty acid profiles, proteolytic activity and processing conditions. Aroma intense compounds like pyrazines and sulfur-containing compounds were limited in cooked beef in the current experimental condition (i.e., relatively low heating temperature). This suggests that higher heating temperature as in the case of roasting is needed for the generation of high aroma notes in meat. Furthermore, proteolytic activity and stability of fatty acids during ageing have a great influence on the generation of flavor components in cooked beef.

• 한국자기공명학회논문지
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• 제24권2호
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• pp.43-46
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• 2020

Huntington's disease (HD) is an inherited neurodegenerative disease caused by abnormal polyglutamine (polyQ) expansion in the huntingtin protein (Htt). There is no cure for HD so far. Although exact molecular mechanism of HD pathogenesis is still elusive, fibril formation of the expanded Htt is linked to the toxicity. In this study, we prepared the expanded Htt containing 46 glutamines, and induced the fibrillation by proteolytic cleavage. Fibrillation of the pathogenic Htt has been monitored by time course NMR experiment. The NMR-based monitoring method could be widely used to screen the candidates to inhibit the fibrillation of the pathogenic Htt.

• BMB Reports
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• 제41권12호
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• pp.827-832
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• 2008

Many age-dependent neurodegenerative diseases are associated with the accumulation of abnormally folded proteins within neurons. One of the major proteolytic pathways in the cell is the autophagy pathway, which targets cytoplasmic contents and organelles to the lysosomes for bulk degradation under various physiological and stressful conditions. Although the importance of autophagy in cellular physiology is well appreciated, its precise roles in neurodegeneration remain largely unclear. Recent studies indicate that components of the endosomal sorting complex required for transport (ESCRT) are important in the autophagy pathway. Reduced activity of some ESCRT subunits leads to the accumulation of autophagosomes and failure to clear intracellular protein aggregates. Interestingly, rare mutations in CHMP2B, an ESCRT-III subunit, are associated with frontotemporal dementia linked to chromosome 3 (FTD3). Mutant CHMP2B proteins seem to disrupt the fusion of autophagosomes and lysosomes in cell culture models. These findings suggest a potential mechanism for the pathogenesis of FTD3 and possibly other neurodegenerative diseases as well.

• 한국동물학회지
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• 제26권4호
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• pp.235-251
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• 1983

배양한 계배 근원세포의 융합기작을 밝혀보기 위해서 분화과정에 있는 근세포를 lactoperoxidase를 촉매로 써서 막표면단백질을 iodination하여 본 결과, 융합의 과정에서 막표면단백질의 정성적 및 정량적 변화를 볼 수 있었다. 융합전의 세포에서 12개의 주요단백질을 검출할 수 있었는데, 융합시의 세포에서는 165K와 93K의 단백질이 새롭게 나타났으며 동시에 245K 단백질의 감소와 저분자 단백질의 증가를 볼 수 있었다. 이 고분자 단백질의 감소는 세포주기와 관계가 있는 것으로 생각되고 있는 세포내 cAMP 수준은 융합에 앞서서 현저한 일시적인 증가를 보였는데, 이와같은 결과는 cAMP의 증가가 세포의 융합의 유발과 관계가 있음을 보여 주는 것이었으며, 분화하는 근원세포에서는 고도의 동조성이 보였다. 아울러, 근세포의 융합과정에서 적어도 4 가지의 iodination된 저분자 단백질을 배양액에서 발견할 수 있었는데, 이들은 막단백질의 가수분해산물로 생각되었고, 역시 세포의 융합과정과 유관할 것으로 추정되었다. 세포막 표면단백질의 변화, 분화과정 중에 배양액 속으로 방출되는 단백질, 융합과 유관한 cAMP의 증가 및 융합과 관련되는 외적 요인의 가능성에 관해서 논의하였다.