D-Cysteine hydrochloride monohydrate

Amino acid analysis is a highly accurate method for characterization of the composition of synthetic peptides. Together with mass spectrometry, it gives a reliable control of peptide quality and quantity before conjugation and immunization. Peptides are hydrolyzed, preferably in gas phase, with 6 M HCl at 110 °C for 20-24 h and the resulting amino acids analyzed by ion-exchange chromatography with post-column ninhydrin derivatization. Depending on the hydrolysis conditions, tryptophan is destroyed, and cysteine also, unless derivatized, and the amides, glutamine and asparagine, are deamidated to glutamic acid and aspartic acid, respectively. Three different ways of calculating results are suggested, and taking the above limitations into account, a quantitation better than 5% can usually be obtained.

Cystathionine γ-lyase (CGL) is a key enzyme in the methionine-cysteine cycle in all living organisms forming cysteine, α-ketobutyrate and ammonia via homocysteine and cystathionine intermediates. Although, human and plant CGLs have been extensively studied at the molecular and mechanistic levels, there has been little work on the molecular and catalytic properties of fungal CGL. Herein, we studied in detail for the first time the molecular and catalytic stability of Aspergillus fumigatus CGL, since conformational instability, inactivation and structural antigenicity are the main limitations of the PLP-dependent enzymes on various therapeutic uses. We examined these properties in response to buffer compositions, stabilizing and destabilizing agents using Differential Scanning Fluorometery (DSF), steady state and gel-based fluorescence of the intrinsic hydrophobic core, stability of internal aldimine linkage and catalytic properties. The activity of the recombinant A.

In this study, a highly efficient chemical vapor generation (CVG) approach is reported for determination of cadmium (Cd). Titanium (III) and titanium (IV) were investigated for the first time as catalytic additives along with thiourea, L-cysteine and potassium cyanide (KCN) for generation of volatile Cd species. Both Ti(III) and Ti(IV) provided the highest enhancement with KCN. The improvement with thiourea was marginal (ca. 2-fold), while L-cysteine enhanced signal slightly only with Ti(III) in H2SO4. Optimum CVG conditions were 4% (v/v) HCl + 0.03 M Ti(III) + 0.16 M KCN and 2% (v/v) HNO3 + 0.03 M Ti(IV) + 0.16 M KCN with a 3% (m/v) NaBH4 solution. The sensitivity was improved about 40-fold with Ti(III) and 35-fold with Ti(IV). A limit of detection (LOD) of 3.2 ng L-1 was achieved with Ti(III) by CVG-ICP-MS. The LOD with Ti(IV) was 6.4 ng L-1 which was limited by the blank signals in Ti(IV) solution. Experimental evidence indicated that Ti(III) and Ti(IV) enhanced Cd vapor generation catalytically; for best efficiency mixing prior to reaction with NaBH4 was critical.

Eight illudane sesquiterpenes were obtained from the wood-decomposing fungus Granulobasidium vellereum (Ellis and Cragin) Jülich; among them were the enantiomers of the known compounds illudin M (1) and dihydroilludin M (4) and the diastereomers of illudin M (2) and illudin S (3), as well as two previously undescribed illudanes (5, 6). The cytotoxicity of compounds 1-4 and 6 was evaluated against two tumor cell lines (Huh7 and MT4), which showed that compounds 1-3 had potent cytotoxic activity, whereas compounds 4 and 6 had no or only moderate effects at concentrations up to 400 μM. Surprisingly, both compounds 2 and 3 were about 10 times more potent than 1. When the chemical reactivity of 1 and 2 was tested, compound 2 was shown to have a substantially higher reaction rate when reacted both with 2 M HCl and with cysteine, indicating that the difference in cytotoxicity is probably due to chemical reactivity and not to enzymatic affinity.