Effect of Ascorbic Acid on Cysteine Requirement of Lactobacilli.
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1. The requirement of some lactobacilli for cysteine, as determined in growth tests with usual chemically defined media, disappears when ascorbic acid in appropriate amounts, or other reducing substance, is incorporated in the medium. Of 5 strains of lactobacilli in this category encountered in a collection of 36 cultures, one was L. casei, the other 4 were heterofermentative L. fermenti. For these organisms the apparent cysteine requirement appears to be a need for a reducing substance and not for cysteine per se. Many L. fermenti strains evidently do not require cysteine though this may not always be apparent with some of the commonly-used synthetic media. 2. In contrast to L. fermenti, other lactobacilli—most L. casei, lactose-negative L. casei, L. acidophilus, and the majority of L. plantarum—require cysteine for growth in the presence of ascorbic acid. The rate of growth of these lactobacilli often is accelerated by ascorbic acid in the presence of either suboptimal or optimal amounts of cysteine. 3. Some implications of these findings concerning microbiological assay of cysteine and the distinguishing characteristics of heterofermentative L. fermenti and homofermentative lactobacilli are discussed.Keywords:
Lactobacillus casei
The effects of Cd on the contents of free cysteine, total glutathione and phytochelatin (PC) were measured in roots of intact maize seedlings. Crude extracts in 100 mM HCl were separated by reverse-phase HPLC and thiols quantitated by continuous addition of Ellman's reagent. Exposure to 3 {mu}M Cd for 15 min caused PCs to appear. The kinetics indicated that shorter PCs were substrates for longer PCs. Total glutathione levels declined with PC synthesis, free cysteine contents changed little. In the 1 cm apical region a high production of PCs occurred with a moderate loss of total glutathione. In the nature region (1-10 cm), PC content was 2.5 fold less than in species and total glutathione levels declined drastically. Exposure to 0.05 {mu}M Cd for 24 h induced PCs, more PCs appeared with greater Cd supplies. The roots produced PCs in excess of that required to chelate the Cd present, as if some PCs were compartmentalized or had not yet formed Cd-PC complexes.
Phytochelatin
Cysteine Metabolism
Thiol
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Вивчено вплив пробіотика Lactobacillus casei В- 7280 у складі стимулюючої підгодівлі на життєдіяльність медоносних бджіл. Сформовано три групи бджіл, по 60-90 у кожній, відібраних з сімей-аналогів за масою, силою сім'ї, віком матки. Дослідження виконані в умовах утримання бджіл в термостаті. Бджоли контрольної (К) групи отримували підгодівлю 60 % цукрового сиропу в кількості 2 мл/групу/добу. Дослідна 1 група бджіл (Д 1) – з 2 мл цукрового сиропу отримувала пробіотик Lactobacillus casei В-7280 у концентрації 109 КУО/мл; дослідна 2 група бджіл (Д 2) – з 2 мл цукрового сиропу отримувала пробіотик Lactobacillus casei В-7280 у концентрації 106 КУО/мл. Підгодівлю бджіл проводили щодобово. Тривалість випоювання сиропу та пробіотика – 30 діб. Фізіологічний стан бджіл реєстрували щодобово впродовж усього періоду дослідження. Проводили підрахунок мертвих і живих бджіл. Активність каталази визначали за допомогою здатності гідрогенпероксиду утворювати із солями молібдену стійкий кольоровий комплекс з фотометруванням розчину на спектрофотометрі. Отримані результати доводять, що пробіотик Lactobacillus casei В-7280 проявляв стимулюючий вплив на життєздатність медоносних бджіл карпатської породи впродовж 30 діб його застосування з цукровим сиропом в умовах лабораторного термостату. Випоювання медоносним бджолам пробіотика Lactobacillus casei В-7280 в дозах 1×109 КУО/мл (Д 1 група) і 1×106 КУО/мл (Д 2 група) за умов лабораторного термостату стимулювало їх життєздатність, що підтверджує більша кількість живих бджіл за 6-денними періодами досліду порівняно з контрольною групою. Отримані результати корелюють з підвищенням каталазної активності тканин організму бджіл і вказують на виражений фізіологічний вплив застосованих доз пробіотика В-7280. Додавання до цукрового сиропу пробіотика В-7280 підвищувало (Р<0,05) каталазну активність тканин бджіл як за дії вищої (Д 1), так і за нижчої (Д 2) доз. Вплив застосованих доз пробіотика Lactobacillus casei В-7280 підвищував життєздатність бджіл за кількістю живих бджіл, що більше виражено на 12, 24 і 30 доби досліду. Середня відносна кількість бджіл в Д 1 та Д 2 групах за 30 діб досліджень перевищувала контрольну групу відповідно на 3,7 і 4,4 %, проте на 24 і 30 доби вказані величини були більшими на 8,6 і 12,3 % в Д 1 і 6,4 і 8,6 % – в Д 2 групах. Ці дані вказують на доцільність використання пробіотика Lactobacillus casei В-7280 у застосованих концентраціях для підвищення життєздатності медоносних бджіл.
Lactobacillus casei
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Abstract— Several recent studies have shown cysteine derivatives can protect against negative effects of UV exposure. In this study, an attempt was made to correlate cellular bioavailability and metabolism of cysteine derivatives with protection against UV‐induced reactive intermediates. Human keratinocytes were treated with cysteine, N ‐ace‐tylcysteine(NAC), cysteine‐ethylester(CYSET) and N‐ acetylcysteine‐ethylester. The uptake of the compounds and their metabolism to cysteine and eventually to glutathione(GSH) was measured. Large differences in uptake were observed, with CYSET resulting in the highest and NAC in the lowest intracellular thiol levels. The increase in intracellular GSH was similar for all derivatives with a maximum of 23‐54% over the control level. Protective efficacy of the derivatives was measured as the inhibition of binding of UV‐induced reactive intermediates from 8‐methoxypsoralen. There was only a small difference between the compounds, with maximum protection of 25‐31%. No relation was found between total intracellular thiol and protection. However, for NAC, there was a linear relation between GSH level and protective efficacy (r = 0.94). Even though this was not clear for the other derivatives(r = 0.55 for CYS; r = 0.60 for CYSET; r = 0.70 for NACET), it indicates that GSH synthesis is an important factor. This was confirmed by experiments using cells with irreversibly inhibited GSH synthesis. Even though the total intracellular thiol level was comparable to uninhibited cells, protection was decreased. We conclude that the intracellular GSH increase is the most important factor in photoprotection by cysteine derivatives.
Thiol
Reactive intermediate
Photoprotection
Cysteine Metabolism
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The ability of astroglia-rich primary cultures derived from the brains of neonatal rats to take up and metabolize various sulfur containing compounds to cysteine was investigated using the content of intracellular glutathione as an indicator. Astroglial cells were partially depleted of glutathione by starvation for 24 h. Subsequent feeding for 4 h with glucose, glycine, and glutamate resulted in a restoration of the glutathione level, if cysteine was present. Substitution of cysteine by cystine during resynthesis of glutathione led to a glutathione content which exceeded that of cysteine-refed cells by 41%. Half-maximal content of glutathione was found at a concentration of about 12 microM cysteine and a maximal content at a concentration of at least 50 microM cysteine. In contrast, no plateau in the glutathione level was reached with increasing concentrations of cystine. The cystine effect could not be due to a contamination, since it was abolished after reduction of cystine by dithiothreitol. Since the cystine effect was not affected by inhibiting gamma-glutamyl transpeptidase, a promotion of cystine uptake by formation of gamma-glutamylcystine can also be excluded. Of the potential cysteine precursors tested, N-acetylcysteine was able to replace cysteine half-maximally at a concentration of 1 mM and fully at 5 mM. Feeding 2-oxothiazolidine-4-carboxylic acid at a concentration of 5 mM resulted in 64% of the glutathione level found in the presence of cysteine. A half-maximal glutathione content was attained at 50 microM 2-oxothiazolidine-4-carboxylic acid. While cystathionine could partially replace cysteine, methionine and homocysteine were not at all able to substitute for cysteine. These results demonstrate that astroglial cells prefer cystine from cysteine for glutathione synthesis and express uptake systems for N-acetylcysteine, 2-oxothiazolidine-4-carboxylic acid, and cystathionine, as well as the enzymes N-deacetylase, 5-oxoprolinase, and cystathionine gamma-lyase.
Dithiothreitol
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Thiol
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Cysteine Metabolism
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Abstract L ‐Cysteine‐glutathione disulfide, a ubiquitous substance present in mammalian cells, was shown to be highly effective in protecting mice against acetaminophen‐induced hepatotoxicity. Since the corresponding D ‐cysteine‐glutathione disulfide was totally ineffective in this regard, an enzymatic mechanism that provides glutathione directly to cells is postulated. © 2003 Wiley Periodicals, Inc. J Biochem Mol Toxicol 17:95–97, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.10069
Acetaminophen
Glutathione disulfide
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Abstract: Cysteine is the rate‐limiting precursor of glutathione synthesis. Evidence suggests that astrocytes can provide cysteine and/or glutathione to neurons. However, it is still unclear how cysteine is released and what the mechanisms of cysteine maintenance by astrocytes entail. In this report, we analyzed cysteine, glutathione, and related compounds in astrocyte conditioned medium using HPLC methods. In addition to cysteine and glutathione, cysteine‐glutathione disulfide was found in the conditioned medium. In cystine‐free conditioned medium, however, only glutathione was detected. These results suggest that glutathione is released by astrocytes directly and that cysteine is generated from the extracellular thiol/disulfide exchange reaction of cystine and glutathione: glutathione + cystine ↔ cysteine + cysteineglutathione disulfide. Conditioned medium from neuronenriched cultures was also assayed in the same way as astrocyte conditioned medium, and no cysteine or glutathione was detected. This shows that neurons cannot themselves provide thiols but instead rely on astrocytes. We analyzed cysteine and related compounds in rat CSF and in plasma of the carotid artery and internal jugular vein. Our results indicate that cystine is transported from blood to the CNS and that the thiol/disulfide exchange reaction occurs in the brain in vivo. Cysteine and glutathione are unstable and oxidized to their disulfide forms under aerobic conditions. Therefore, constant release of glutathione by astrocytes is essential to maintain stable levels of thiols in the CNS.
Glutathione disulfide
GPX1
Thiol
Cysteine Metabolism
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