• BMB Reports
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• 제50권8호
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• pp.401-410
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• 2017

The protein disulfide isomerase (PDI) family is a group of multifunctional endoplasmic reticulum (ER) enzymes that mediate the formation of disulfide bonds, catalyze the cysteine-based redox reactions and assist the quality control of client proteins. Recent structural and functional studies have demonstrated that PDI members not only play an essential role in the proteostasis in the ER but also exert diverse effects in numerous human disorders including cancer and neurodegenerative diseases. Increasing evidence suggests that PDI is actively involved in the proliferation, survival, and metastasis of several types of cancer cells. Although the molecular mechanism by which PDI contributes to tumorigenesis and metastasis remains to be understood, PDI is now emerging as a new therapeutic target for cancer treatment. In fact, several attempts have been made to develop PDI inhibitors as anti-cancer drugs. In this review, we discuss the properties and diverse functions of human PDI proteins and focus on recent findings regarding their roles in the state of diseases including cancer and neurodegeneration.

• Macromolecular Research
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• 제13권1호
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• pp.30-38
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• 2005

Sulfur-cured gum natural rubber vulcanizates were devulcanized using two different concentrations of diallyl disulfide. The devulcanization process was performed at $110^{\circ}C$ min in an open two-roll cracker-cum-mixing mill. Natural rubber vulcanizates having various sulfur/accelerator ratios were used to study the cleavage of monosulfide, disulfide, and polysulfide bonds. The properties of devulcanized natural rubber increased upon increasing the disulfide concentration and the mechanical properties of the revulcanized natural rubber increased upon decreasing the sulfur content in the original rubber vulcanizates. The scorch time and the maximum state of cure both increased when the ground vulcanizates were treated with higher amounts of disulfide. TGA and DMA were conducted to study the effects of the devulcanization on the thermal stability and the $T_g$ behavior of the vulcanizates. SEM analysis was conducted to study how the failure mechanism was affected by the devulcanization process. It was possible to recover $70-80\%$ of the original gum rubber properties by using this process. From IR spectroscopic analysis, we observed that the oxidation of the main chains did not occur during high-temperature milling.

• Applied Biological Chemistry
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• 제31권3호
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• pp.274-283
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• 1988

Aqualysin I is an alkaline serine protease which is secretet into the culture medium by Thermus aquaticus YT-1, an extreme thermophile. Aqualysin I was purified, and its partial amino acid sequence was determined. The gene encoding aqualysin I was cloned into E. coli using synthetic oligodeoxyribonucleotides as hybridization probes. The nucleotide sequence of the cloned DNA was determined. The primary structure of aqualysin I, deduced from the nucleotide sequenc, agreed with the determid amino acid sequences, including the $NH_2-$ and COOH terminal sequence of the tryptides derived from aqualysin I. Aqualysin I comprised 281 amino acid residues and its molecular mass was determined to be 28350. On alignment of the whole amino acid sequence, aqualysin I showed high sequence homology with the subtilisin type serine protease, and 43% identity with proteinase K, 37-30% with subtilisins and 34% with thermitase. Extremely high sequence identity was observed in the regions containing the active-site residues, corresponding to Asp32, His64 and Ser221 of subtilisin BPN'. Aqualysin I contains two disulfide bonds, Cys67-Cys99 and Cys163-Cys194, and these disulfide bonds seem to contribute to the heat stability of the enzyme. The determined positions of the twe disulfide bonds of aqualysin I agreed with those predicted previously on the basis of computer graphics of the crystallographic data for subtilisin BPN'. Therefore, these findings sugests that the three-dimensional structure of aqualysin I is similar to that of subtilisin BPN' Aqualysin I is produced as a lage precursor, which contains $NH_2-$ and COOH- terminal portions besides the mature protease sequence.

• BMB Reports
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• 제33권6호
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• pp.493-498
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• 2000

Aquifex pyrophilus, a hyperthermophilic bacterium, has a serine-type protease that is located at the cell wall fraction with a mature size of 43 kDa. Molecular cloning of the protease gene revealed that it has an ORF of 619 amino acids with homologous catalytic site of serine-type proteases [Choi, I.-G., Bang, W.-K., Kim, S.-H., Yu, G. Y., J. Biol. Chem. (1999), Vol. 274, pp. 881-888]. Constructs containing different regions of the protease gene, including a alanine-substituted mutant at the active site serine, were constructed, and the factors affecting the expression level of the cloned protease gene in E. coli were examined. The presence of the C-terminus hydrophobic region of the protease hindered over-expression in E. coli. Also, the proteolytic activity of the expressed protein appeared to toxic to E. coli. An inactive form that deleted both of the N-terminal signal sequence and the C-terminal polar residues was over-expressed in a soluble form, purified to homogeneity, and its thermostability examined. The purified protein showed three disulfide bonds and three free sulfhydryl group. The thermal denaturation temperature of the protein was measured around $90^{\circ}C$ using a differential scanning calorimeter and circular dichroism spectrometry. The disulfide bonds were hardly reduced in the presence of reducing agents, suggesting that these disulfide bonds were located inside of the protein surface.

• Molecules and Cells
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• 제38권8호
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• pp.715-722
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• 2015

In Gram-negative bacteria in the periplasmic space, the dimeric thioredoxin-fold protein DsbC isomerizes and reduces incorrect disulfide bonds of unfolded proteins, while the monomeric thioredoxin-fold protein DsbA introduces disulfide bonds in folding proteins. In the Gram-negative bacteria Salmonella enterica serovar Typhimurium, the reduced form of CueP scavenges the production of hydroxyl radicals in the copper-mediated Fenton reaction, and DsbC is responsible for keeping CueP in the reduced, active form. Some DsbA proteins fulfill the functions of DsbCs, which are not present in Gram-positive bacteria. In this study, we identified a DsbA homologous protein (CdDsbA) in the Corynebacterium diphtheriae genome and determined its crystal structure in the reduced condition at $1.5{\AA}$ resolution. CdDsbA consists of a monomeric thioredoxin-like fold with an inserted helical domain and unique N-terminal extended region. We confirmed that CdDsbA has disulfide bond somerase/reductase activity, and we present evidence that the N-terminal extended region is not required for this activity and folding of the core DsbA-like domain. Furthermore, we found that CdDsbA could reduce CueP from C. diphtheriae.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.548-548
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• 2003

• 한국잠사학회:학술대회논문집
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• 한국잠사학회 2003년도 제46회 춘계 학술연구 발표회
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• pp.45-45
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• 2003

Protein disulfide isomerase (PDO) is an essential protein which is localized to the endoplasmic reticulum (ER) of eukaryotic cells. It catalyses the formation and isomerization of disulfide bonds during the folding of secretory proteins. We have isolarted a cDNA encoding PDI from Bombyx mori (bPDI), in which an open reading frame of 494 mino acid (55.6kDa) is shown. (omitted)

• Bulletin of the Korean Chemical Society
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• 제7권5호
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• pp.331-334
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• 1986

The crystal structure of thiamin tetrahydrofurfuryl disulfide, one of the ring-opened derivatives of thiamin, has been determined by the X-ray diffraction methods. The crystal is monoclinic with cell dimensions of a = 8.704 (1), b = 11.207 (2), c = 21.260 (3) ${\AA}$ and ${\beta}$ = 92.44 (2)$^{circ}$, space group P2$_{1}$/c and Z = 4. The structure was solved by direct methods and refined to R = 0.076 for 1252 observed reflections measured on a diffractometer. The molecule assumes a folded conformation in which the pyrimidine and the tetrahydrofurfuryl rings are on the same side of the ethylenic plane. The pyrimidinyl, N-formyl and ethylenic planes are mutually perpendicular to each other and the N(3)-C(4) bond retains a single bond character. The structure is stabilized by an intramolecular N(4'${\alpha})-H{\cdots}O(2{\alpha}$) hydrogen bond. The molecules are connected via N(4'${\alpha}$)-H{\cdots}(N3')$ and O(5${\gamma})-H{\cdots}(N1')$ hydrogen bonds, forming a two-dimensional hydrogen-bonding network. The tetrahydrofurfuryl ring is dynamically disordered. The overall conformation as well as the packing mode is very similar to that of thiamin propyl disulfide.

• Bulletin of the Korean Chemical Society
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• 제29권6호
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• pp.1190-1194
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• 2008

• BMB Reports
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• 제28권1호
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• pp.17-20
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• 1995

Thioredoxin reductase is a flavoprotein oxidoreductase catalyzing the reduction of a cystine disulfide in thioredoxin. Thioredoxin, in turn, can reduce disulfide bonds in other proteins and serves as a reducing agent in enzymatic reactions such as those of ribonucleotide reductase and methionine sulfoxide reductase. In this work thioredoxin reductase was found to directly reduce DTNB in the absence of thioredoxin. This new reactivity of E. coli thioredoxin reductase was produced by relatively high concentrations of univalent cations such as $Na^+$, $K^+$, $Li^+$, and ${NH_4}^+$, and it appeared with the oxidation of NADPH. These results indicate that E. coli thioredoxin reductase may be slightly modified by univalent cations, and the modified enzyme directly reacts with DTNB. This DTNB-reducing activity offers a new assay method for E. coli thioredoxin reductase.