Schwefel und Selen: Bedeutung der Oxidationsstufe für Struktur und Funktion von Proteinen

Jacob, Claus; Giles, Gregory I.; Giles, Niroshini M.; Sies, Helmut

doi:10.1002/ange.200300573

Cited by 75 publications

(32 citation statements)

References 129 publications

(126 reference statements)

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“…Holmes and Lawton [52], for the first time, reported about conversion of cysteine into dehydroalanine as a result of its oxidative elimination during desulfurization. Some metals have also been reported to mediate chemistry of keratinous cysteine due to its natural affinity towards metals [53]. For instance, nickel and palladium are used to mediate the selective reduction of cysteine to alanine [54].…”

Section: Keratin Modificationmentioning

confidence: 99%

Untitled

2013

J Food Processing & Beverages

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A great deal of environmental concerns, oil price hike, and rapid oil consumption with finite nature of oil reserves in addition to consumer demand is driving research into renewable, biodegradable, inexpensive, and abundantly available biopolymers in material chemistry. Poultry feathers consist of keratin protein with several amino acids especially cysteine as a major component. Keratin is an original raw material that has great potential to be used in the development of novel fibrous composite materials. Being very effective biopolymer, keratin possesses numerous functional properties, bioactivities, and chemical applications in material chemistry, for example, keratin based gels, films, nano/micro-particles, and beads are of paramount importance. Modified keratin also serves as a biosorbent for removing toxic metal ions from water resources on account of exceptionally important role of functional groups for keratin-metal binding. This review focuses on the recent advances of keratin in material chemistry including its significant role as biosorbent in green chemistry.

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Section: Keratin Modificationmentioning

confidence: 99%

Untitled

2013

J Food Processing & Beverages

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“…[2,3] Actually, some of the synthetic phenols developed show excellent features, such as very high reactivity towards peroxyl radicals and improved air stability. [4] Another active area of research is the study of preventive antioxidants, [5] compounds often containing divalent S, Se, or Te atoms in the molecular skeleton, [6] which inhibit the formation of initiating free radicals by decomposing hydroperoxides by a nonradical process. Chalcogen-substituted phenols have been found to possess both chain-breaking and preventive antioxidant activities.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Antioxidant Activity of Hydroxy‐Substituted 4‐Thiaflavanes: A Proof‐of‐Concept Study

Viglianisi

Bartolozzi

Pedulli

et al. 2011

Chemistry A European J

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The design and the synthesis of a new family of hydroxy-4-thiaflavanes, in which the reactive phenolic OH is ortho to the sulfur atom of the benzofused oxathiin ring, allowed to prepare antioxidants that show rate constants for the reaction with peroxyl radicals (k(inh)), and bond dissociation energies (BDE), of the ArO-H group identical to those of α-tocopherol, the main component of vitamin E and the most effective lipophilic antioxidant known in nature. The peculiar conformation of the six-membered heterocyclic ring prevents the formation of an intramolecular hydrogen bond between the OH group and the S atom, while ensuring a good stabilization by electron donation of the phenoxyl radical formed after the reaction with peroxyl radicals. The preparation of these compounds was achieved through an inverse electron demand hetero Diels-Alder reaction of styrenes with o-thioquinones, in turn prepared from accurately designed 1,3-dihydroxy arenes. Properly arranging the substitution pattern on the aromatic ring, as in derivatives 9 and 11, allowed to reach values of k(inh) up to 4.0×10(6) M(-1) s(-1) and BDE((OH)) of 77.2 kcal mol(-1). This approach represents an innovative way to obtain highly active antioxidants without using strongly electron donating alkylamino groups which are associated with adverse toxicological profiles.

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“…This selectivity is possible not only because the pK a (SeH) value of SeCys is 5.2, which is much lower than the pK a (SH) value of 8.3 of its thiol counterpart cysteine (Cys), but also because selenols behave as stronger nucleophiles than thiols (see Scheme 1). [16] An attempt based on a similar concept failed to confer specific probing ability toward selenols with existing fluorescent thiol probes such as monobromobimane, 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole, N-(1-pyrene)maleimide, and N-(7-dimethylamino-4-methylcoumaryl)maleimide. [9] In contrast to these probes, BESThio was found to exert Janus-faced functions switched by a proper choice of the pH of the media (Scheme 1).…”

mentioning

confidence: 98%