• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.10 no.1
• /
• pp.11-15
• /
• 1977

Brownish discoloration develops very rapidly in the storage of dried oyster. This undesirable browning is mainly caused by the series of reactions of sugar-amino condensation, enzymatic oxidation of tyrosine and/or the oxidative rancidity of lipids in the tissue of oyster. Sulfites are commonly used as inhibitors for Maillard type browning reactions in agricultural products. The inhibitory effect of sulfite treatment on canned oysters was also confirmed in some investigations. The results suggested that sulfites not only work on blocking tile amadori rearrangement but also on the reduction of free tyrosine which retards the progress of enzymatic oxidation of tyrosine tyrosinase. In this paper, the effect of sodium sulfite treatment on the reduction of reducing sugar and free tyrosine as a function i)f browning inhibition in oyster was tested and other treatment with glucose-oxidase and yeast were also applied. In preparation of samples, fresh oysters were soaked in sodium sulfite solution by various concentration for different treating times, washed in running water to remove the sulfite residue, and finally dried in the shade. In the result, the treatment of sodium sulfite was certainly effective on the reduction of both free tyrosine and reducing sugars in fresh oyster. The best results were obtained by the treatment of 0.5M sodium sulfite solution for 60 minutes each for soaking and washing. Treatment with, glucose-oxidase and yeast solutions, however, did appear somewhat effective but it required so much time for a certain effect that it seemed not practically applicable.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.1
• /
• pp.17-22
• /
• 2009

The mixotrophic growth with methanol plus thiosulfate was examined in nutrient-limited mixotrophic condition for Methylobacterium goesingense CBMB5 and Methylobacterium fujisawaense CBMB37. Thiosulfate oxidation increased the growth and protein yield in mixotrophic medium that contained 150mM methanol and 20mM sodium thiosulfate, at 144 h. Respirometric study revealed that thiosulfate was the most preferable reduced inorganic sulfur source, followed by sulfite and sulfur. M. goesingense CBMB5 and M. fujisawaense CBMB37 oxidized thiosulfate directly to sulfate, and intermediate products of thiosulfate oxidation such as polythionates, sulfite, and sulfur were not detected in spent medium and they did not yield positive amplification for tested soxB primers. Enzymes of thiosulfate oxidation such as rhodanese and sulfite oxidase activities were detected in cell-free extracts of M. goesingense CBMB5, and M. fujisawaense CBMB37, and thiosulfate oxidase (tetrathionate synthase) activity was not observed. It indicated that both the organisms use the "non-S4 intermediate" sulfur oxidation pathway for thiosulfate oxidation. It is concluded from this study that M. goesingense CBMB5, and M. fujisawaense CBMB37 exhibited mixotrophic metabolism in medium containing methanol plus thiosulfate and that thiosulfate oxidation and the presence of a "Paracoccus sulfur oxidation" (PSO) pathway in methylotrophic bacteria are species dependant.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
• /
• 1993.12a
• /
• pp.19-20
• /
• 1993

농산물의 수확 후 취급이나 가공중에 일어나는 효소적갈변 현상은 외관의 변색에 의한 소비자의 기호성을 저하시킬 뿐만 아니라 상품의 가치를 하락시키며, 경제적인 손실을 초래함으로서 현재 식품에 종사하는 기술자나 가공업자에게 가장 관심이 있는 분야이다. 효소적갈변의 주역을 담당하고 있는 polyphenol oxidase(PPO)(EC1.14, 18.1)은 대부분의 식품에 존재하고 있으며 monophenol의 hydroxylation에 의한 o-diphenol화합물의 형성반응(cresolase)과 o-diphenol화합물의 o-quinone으로의 산화반응(catecholase)을 촉배한다. 그리고 여기서 일단 생성된 o-quinone은 다시 다른 o-quinone이나 그밖의 단백질, 아미노산, 환원당 등의 여러 성분들과 상호 반응하여 갈변식품의 특유의 색소인 melanine을 형성한다. 효소적갈변에 의한 품질의 저하는 식품가공산업에서 해결되어야 할 하나의 큰 과제이다. 현재까지 식품산업에서 가장 널리 쓰이고 있는 효소적갈변 저해제는 sylfite류 이다. 그들은 새우의melanosis(blackspot)를 억제하며, 감자, 버섯, 사과와 다른 과채류의 갈변을 방지할 뿐 아니라 쥬우스와 포도주의 off flavors를 일으키는 폴리페놀 플리머의 형성을 감소 시킨다. 그러나 최근 sulfite가 사람의 건강에 좋지않는 부작용을 일으키며, 특히 천식을(asthma)을 지니고 있는 사람이 sulfite가 함유된 식품을 먹었을 경우 사망을 초래할 수 있어 식품첨가물로서 그들의 사용이 미국 FDA에 의해 재평가되고 있다. 최근에 FDA는 셀러드바에서의 sulfite사용을 금지 시켰으며 점차 감자가공품에의 사용을 금지하는 방향으로 나아가고 있다. 따라서 현재 실질적이고 기능적인 sulfite의 대체 화합물의 개발이 절실히 필요한 실정이다. 이러한 배경으로 본 강연에서는 효소적갈변 저해제의 개발과 그들의 식품가공에의 적용 현환 및 화장품, 의약품으로의 응용에 대해 설명하고자 한다.

• Journal of Ginseng Research
• /
• v.37 no.1
• /
• pp.117-123
• /
• 2013

Polyphenol oxidase (PPO) was purified from fresh ginseng roots using acetone precipitation, carboxymethyl (CM)-Sepharose chromatography, and phenyl-Sepharose chromatography. Two isoenzymes (PPO 1 and PPO 2) were separated using an ion-exchange column with CM-Sepharose. PPO 1 was purified up to 13.2-fold with a 22.6% yield. PPO 2 bound to CM-Sepharose, eluted with NaCl, and was purified up to 22.5-fold with a 17.4% yield. PPO 2 was further chromatographed on phenyl-Sepharose. The molecular weight of the purified PPO 2 from fresh ginseng was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was about 40 kDa. The optimum temperature and pH were $20^{\circ}C$ and 7.0, respectively, using catechol as a substrate. Pyrogallol showed the highest substrate specificity. The effect of a PPO inhibitor showed that its activity increased slightly in the presence of a low concentration of citric acid. High concentrations of acidic compounds and sulfite agents significantly inhibited purified ginseng PPO 2.

• YAKHAK HOEJI
• /
• v.40 no.1
• /
• pp.65-71
• /
• 1996

Characterization of Polyphenol oxidase (PPO) in Perillae Folium, particullarly inhibitor studies were investigated. This enzyme was stable at pH 5.0 and the residual activity of PPO at ${\geq}$ ph 5.5 was estimated to be very low. PPO activity was decreased slightly by adding amino acid with catechol as a substrate, particullary PPO activity was inhibited markedly by cystein, histidine, lysine and arginine. In the absorption spectra of the product formed when catechol was oxidized by PPO, with a ${\lambda}_{max}$ at 410nm, the peak shifted toward ${\lambda}_{max}$ 520nm by addition of L-proline. At relatively low concentrations($10^{-3}M$), sulfite and dithiothreithol completely inhibited PPO activity. Inhibition of PPO activity by amino acids and inhibitors increased or decreased depending on the pH used to measure it.

• Journal of Environmental Health Sciences
• /
• v.19 no.1
• /
• pp.66-70
• /
• 1993

Introduction : Methanethiol is a toxicant that is a byproduct in the industrial process (oil refinery), and it is produced in vivo from methionine via transamination in case of its overintake. And it also can be generated by the action of mucosal thiol Smethyltransferase on hydrogen sulfite which is formed by anaerobic bacteria in the intestinal tract. The toxicity of methanethiol has often been suggested as one of endogenous factors involved in the pathogenesis of hepatic encephalopathy. Furthermore, methanethiol could cause the membrane damage and inhibition of some membrane protective enzymes.

• Journal of The Korean Society of Inherited Metabolic disease
• /
• v.14 no.1
• /
• pp.10-18
• /
• 2014

Recent advances in the diagnosis and treatment of inborn errors of metabolism have improved substantially the prognosis of many of these diseases, if diagnosed early enough before irreversible damage occurs. This makes it essential that the practicing pediatrician, especially neonatologists be familliar with the clinical presentations and systematic approaches of these disorders. Characteristic clinical presentations, methods of systematic approach and typing of various disorders is discussed in this review. The signs of neurological dysfunctions of many IEMs manifesting in the neonatal period is very nonspecific, such as poor feeding, poor sucking, apnea or tachypnea, vomiting, hypertonia, hypotonia, seizure, letharginess, consciousness change and coma. Many other non-metabolic severe disorders of neonatal period such as neonatal sepsis and intracerebral hemorrhage share these nonspecific symptoms. Hyperammonemia, metabolic acidosis, ketosis and hyperlatic acidemia are observed in many of these conditions but there are exceptions in which conditions all basal laboratory tests are normal, such as NKH, sulfite oxidase deficiency and peroxisomal disorders. According to the results of basal laboratory tests, IEMs in the neonatal period can be categorized in to 6 types. Grouping of IEMs into 6 types will make confirmatory tests and early emergency treatment more efficient.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.26 no.3
• /
• pp.214-220
• /
• 1993

Browning of ascidian, Halocynthia roretzi, meat occurres very rapidly when skinned off or cut during processing and it resulted the quality loss of fresh frozen, dehydrated or fermented products. In this study, the causes of color development and prevention of browning were experimented. The browning of ascidian meat may be occurred enzymatically by a tyrosinase contained in meat and viscera which acted specifically on L-tyrosine as a substrate rather than on catechol. Activity of the enzyme in viscera was three times higher than in meat. The optimum pH and temperature on the tyrosinase activity of crude enzyme obtained from ascidian was 6.0 and $30{\sim}35^{\circ}C$, respectively. The enzyme was inactivated heating at $80^{\circ}C$ for 3 minutes or $90{\sim}100^{\circ}C$ for 1 minute and it was inhibited by $0.1{\sim}0.5mM$ solutions at ascorbic acid, sodium hydrogen sulfite, cystein, citric acid, cyanide but only sodium hydrogen sulfite treatment was effective to retard such a high content of enzyme as in case of viscera. In practical use for processing of ascidian meat browning was retarded by dipping the viscera removed ascidian meat in 0.2M citric acid for 5 minutes or $0.2\%$ sodium hydrogen sulfite solution for 1 minute resulting in sulfur dioxide residue less than 100 ppm.

• Journal of The Korean Society of Inherited Metabolic disease
• /
• v.14 no.2
• /
• pp.123-134
• /
• 2014

Recent advances in the diagnosis and treatment of inborn errors of metabolism (IEM) have improved substantially the prognosis of many of these diseases, if diagnosed early enough before irreversible damage occurs. Diseases of inborn errors of metabolism are so diverse over several hundred disease up to now and may be several thousand in near future, and these diversities of IEMs make clinicians embarassed. The signs of neurological dysfunctions of many IEMs manifesting in the neonatal period is very nonspecific, such as poor feeding, poor sucking, apnea or tachypnea, vomiting, hypertonia, hypotonia, seizure, letharginess, consciousness change and coma. But after neonatal period, the signs of neurological deficits become specific and localized. The results of routine basal laboratory tests such as metabolic acidosis, hyperammonemia, lactic acidemia, ketonemia or hyperuricemia can give very important clinical clues for the diagnosis of IEMs. Even no abnormal findings on routine laboratory test could be very important clue for NKH, sulfite oxidase deficiency and peroxisomal disorders. These various clinical manifestations of these diverse diseases can be categorized and summarized. This makes it essential that the practicing clinicians be familiar with the clinical presentations and symptomatic and systematic approaches of these disorders. Characteristic clinical presentations, methods of symptomatic and systematic approach and typing of various disorders is discussed in this review.