• BMB Reports
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• 제38권1호
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• pp.58-64
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• 2005

Myo-inositol monophosphate phosphatase (IMPP) is a key enzyme in the phosphoinositide cell-signaling system. This study found that incubating the IMPP from a porcine brain with pyridoxal-5'-phosphate (PLP) resulted in a time-dependent enzymatic inactivation. Spectral evidence showed that the inactivation proceeds via the formation of a Schiff's base with the amino groups of the enzyme. After the sodium borohydride reduction of the inactivated enzyme, it was observed that 1.8 mol phosphopyridoxyl residues per mole of the enzyme dimer were incorporated. The substrate, myo-inositol-1-phosphate, protected the enzyme against inactivation by PLP. After tryptic digestion of the enzyme modified with PLP, a radioactive peptide absorbing at 210 nm was isolated by reverse-phase HPLC. Amino acid sequencing of the peptide identified a portion of the PLP-binding site as being the region containing the sequence L-Q-V-S-Q-Q-E-D-I-T-X, where X indicates that phenylthiohydantoin amino acid could not be assigned. However, the result of amino acid composition of the peptide indicated that the missing residue could be designated as a phosphopyridoxyl lysine. This suggests that the catalytic function of IMPP is modulated by the binding of PLP to a specific lysyl residue at or near its substrate-binding site of the protein.

• 한국식품영양과학회지
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• 제13권3호
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• pp.231-237
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• 1984

서해산(西海産) 큰구슬우렁이의 보다 효율적(效率的)인 이용방안(利用方案)을 모색하기 위하여 시도(試圖)한 보일드통조림의 가열살균조건구명(加熱殺菌條件究明) 결과(結果)는 다음과 같다. 1. 큰구슬우렁이생육(生肉)은 고단백(高蛋白), 저지방식품(低脂肪食品)이었으며, 특(特)히 탄수화물함량(炭水化物含量)은 1% 전후(前後)였다. 2. 가열처리시(加熱處理時) 응고성물질(凝固性物質)은 액즙(液汁) 1ml당(當) $0.37{{\sim}}0.40g\;N$. 이상에서만 응고현상(凝固現象)이 일어났다. 따라서 $105^{\circ}C$, 20분(分), $110^{\circ}C$, 40분(分), $115^{\circ}C$, 20분(分)이상 처리시에만 발견(發見)할 수 있었다. 3. 유효성(有效性) lysine은 $110^{\circ}C$, 20분(分)보다는 $125^{\circ}C$, 20분(分)에서 12% 감소(減少)하는 반면, 20분(分)에서 109분(分)까지는 약(約) $17%{{\sim}}22.8%$의 변화(變化)를 보였다. 4. 각 처리구(處理區)의 생균검출(生菌檢出)은 $110^{\circ}C$, 80분(分), $115^{\circ}C$, 40분(分) 이상에서는 검출(檢出)되지 않았다. 5. 큰구슬우렁이 생육(生肉)에서는 tryptophan이 제한(制限)아미노산이었으며, 다른 패류(貝類)의 약(約) 57%(0.83g/16g N.) 밖에 되지 않았고, 보일드육(肉)에서는 methionine (보유율 87%)이 가장 많이 손상(損傷)되었다. 또한 PPDRI치(値)는 생육(生肉) 63.16, 보일드육(肉) 65.85($115^{\circ}C$, 40분(分) 처리(處理)로 생육(生肉)보다 가열처리육(加熱處理肉)이 높았다. 6. 이상의 결과(結果)로 보아 최적가열살균온도(最適加熱殺菌溫度) 및 시간(時間)은 생균수(生菌數), 응고성물질(凝固性物質), 유효성(有效性) lysine을 감안하여 $115^{\circ}C$, 40분(分) 처리(處理)가 바람직하다고 생각되었다.

• BMB Reports
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• 제53권11호
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• pp.576-581
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• 2020

Dimethylation of the histone H3 protein at lysine residue 9 (H3K9) is mediated by euchromatin histone methyltransferase II (EHMT2) and results in transcriptional repression of target genes. Recently, chemical inhibition of EHMT2 was shown to induce various physiological outcomes, including endoplasmic reticulum stress-associated genes transcription in cancer cells. To identify genes that are transcriptionally repressed by EHMT2 during apoptosis, and cell stress responses, we screened genes that are upregulated by BIX-01294, a chemical inhibitor of EHMT2. RNA sequencing analyses revealed 77 genes that were upregulated by BIX-01294 in all four hepatic cell carcinoma (HCC) cell lines. These included genes that have been implicated in apoptosis, the unfolded protein response (UPR), and others. Among these genes, the one encoding the stress-response protein Ras-related GTPase C (RRAGC) was upregulated in all BIX-01294-treated HCC cell lines. We confirmed the regulatory roles of EHMT2 in RRAGC expression in HCC cell lines using proteomic analyses, chromatin immune precipitation (ChIP) assay, and small guide RNA-mediated loss-of-function experiments. Upregulation of RRAGC was limited by the reactive oxygen species (ROS) scavenger N-acetyl cysteine (NAC), suggesting that ROS are involved in EHMT2-mediated transcriptional regulation of stress-response genes in HCC cells. Finally, combined treatment of cells with BIX-01294 and 5-Aza-cytidine induced greater upregulation of RRAGC protein expression. These findings suggest that EHMT2 suppresses expression of the RRAGC gene in a ROS-dependent manner and imply that EHMT2 is a key regulator of stress-responsive gene expression in liver cancer cells.

• The Korean Journal of Physiology and Pharmacology
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• 제3권3호
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• pp.251-261
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• 1999

The effects of carnosine and related compounds (CRCs) including anserine, homocarnosine, histidine, and ${\beta}-alanine$ on monosaccharide autoxidation and $H_2O_2$ formation were investigated. The incubation of CRCs with D-glucose, D-glucosamine, and D, L-glyceraldehyde at $37^{\circ}C$ increased the absorption maxima at 285 nm, 273 nm, and $290{\sim}330$ nm, respectively. D, L-glyceraldehyde was the most reactive sugar with CRCs. The presence of copper strongly stimulated the reaction of carnosine and anserine with D-glucose or D-glucosamine. Carnosine and anserine stimulated $H_2O_2$ formation from D-glucose autoxidation in a dose-dependent manner in the presence of 10 ${\mu}M$ Cu (II). The presence of human serum albumin (HSA) decreased their effect on $H_2O_2$ formation. Carnosine and anserine has a biphasic effect on ${\alpha}-ketoaldehyde$ formation from glucose autoxidation. CRCs inhibited glycation of HSA as determined by hydroxymethyl furfural, lysine residue with free ${\varepsilon}-amino$ group, and fructosamine assay. These results suggest that CRCs may be protective against diabetic complications by reacting with sugars and protecting glycation of protein.