scholarly journals SULFHYDRYL AND DISULFIDE GROUPS OF PROTEINS

1936 ◽  
Vol 19 (3) ◽  
pp. 439-450 ◽  
Author(s):  
A. E. Mirsky ◽  
M. L. Anson
Keyword(s):  
Crystalline Lens ◽  
Iron Porphyrin ◽  
Lens Protein ◽  
Native State ◽  
Lens Proteins ◽  
Sh Groups ◽  
Ph Range

Hemoglobin and the proteins of the crystalline lens contain active SH groups while in the native state, the number of active groups increasing as the pH rises. All the SH groups of denatured globin and of the denatured lens proteins are active at a pH so low that practically none of the SH groups of native hemoglobin and of native lens protein are active. The effect of denaturation on the SH groups of a protein is to extend towards the acid side the pH range of their activity. It is possible to oxidize the iron-porphyrin and the SH groups of hemoglobin independently of each other.

Cataract Induction by 1,2-Naphthoquinone II. Mechanism of Hydrogenperoxide Formation and Inhibition by Iodide

1991 ◽  
Vol 46 (3-4) ◽  
pp. 285-290
Author(s):  
R. Kroner ◽  
E. Kleber ◽  
E. F. Elstner
Keyword(s):  
Oxygen Uptake ◽  
Protein Modification ◽  
Oxygen Activation ◽  
Redox Cycling ◽  
Lens Protein ◽  
Dependent Manner ◽  
Yield Losses ◽  
Concentration Dependent Manner ◽  
Glutathione Conjugation ◽  
Sh Groups

Naphthalene cataract is probably due to peroxide production through naphthoquinone (NQ) redox cycling and/or glutathione conjugation. Both mechanisms yield losses of essential SH-groups in cristallins and are thus probably involved in protein modification finally visible as lens opacity. 1,2-N aphthoquinone produces H2O2 in the presence of either ascorbate, glutathione, NADH or - to a lesser extend - by homogenates of lens protein preparations. In the presence of 1,2-naphthoquinone and the above reductive additions, both, oxygen uptake and H2O2 formation can be observed. Reductive oxygen activation in these systems are diminuated by iodide in a concentration-dependent manner. Since maleimide-treated proteins are less capable to activate oxygen by 1,2-naphthoquinone, a direct oxygen activation by the interactions of 1,2-naphthoquinone with protein-SH is indicated. Catalysis of “diaphorase”-type (dia) enzymes via NADH - dia - 1,2-NQ - O2 seems not to operate in hydrogenperoxide production during 1,2-naphthoquinone lens toxicity.

scholarly journals Multiple changes in lens protein composition associated with the CatFr gene in the mouse

1972 ◽  
Vol 19 (3) ◽  
pp. 241-249 ◽  
Author(s):  
T. H. Day ◽  
R. M. Clayton
Keyword(s):  
Mus Musculus ◽  
Protein Composition ◽  
General Tendency ◽  
Lens Protein ◽  
Lens Proteins ◽  
Quantitative Changes

SUMMARYThe ocular cataracts produced by the dominant CatFr gene in the mouse, Mus musculus, are associated with quantitative changes in the lens proteins (crystallins). The three classes of crystallin are affected differentially in homozygotes. Heterozygotes show a smaller effect. The quantitative levels of crystallin subunits are also affected and these changes are different for each subunit. The overall loss in protein is not readily explicable hi terms of a generalised leakage or a general tendency to insolubilisation. Possible mechanisms for the action of the gene are suggested.

scholarly journals Structure Elucidation of a Novel Yellow Chromophore from Human Lens Protein

2004 ◽  
Vol 279 (44) ◽  
pp. 45441-45449 ◽  
Author(s):  
Rongzhu Cheng ◽  
Qi Feng ◽  
Ognyan K. Argirov ◽  
Beryl J. Ortwerth
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Water Soluble ◽  
Human Lens ◽  
Lens Protein ◽  
Two Dimensional ◽  
Cross Link ◽  
Lens Proteins ◽  
Lysine Residues ◽  
Normal Human

We report here the isolation of a novel acid-labile yellow chromophore from the enzymatic digest of human lens proteins and the identification of its chemical structure by liquid chromatography-mass spectrometry, liquid chromatography-tandem mass spectrometry, and1H,13C, and two-dimensional NMR. This new chromophore exhibited a UV absorbance maximum at 343 nm and fluorescence at 410 nm when excited at 343 nm. Analysis of the purified compound by reversed-phase HPLC with in-line electrospray ionization mass spectrometry revealed a molecular mass of 370 Da. One- and two-dimensional NMR analyses elucidated the structure to be 1-(5-amino-5-carboxypentyl)-4-(5-amino-5-carboxypentylamino)-3-hydroxy-2,3-dihydropyridinium, a cross-link between the ϵ-amino groups of two lysine residues, and a five-carbon ring. Because this cross-link contains two lysine residues and a dihydropyridinium ring, we assigned it the trivial name of K2P. Quantitative determinations of K2P in individual normal human lens or cataract lens water-soluble and water-insoluble protein digests were made using a high-performance liquid chromatograph equipped with a diode array detector. These measurements revealed a significant enhancement of K2P in cataract lens proteins (613 ± 362 pmol/mg of water-insoluble sonicate supernatant (WISS) protein or 85 ± 51 pmol/mg of WS protein) when compared with aged normal human lens proteins (261 ± 93 pmol/mg of WISS protein or 23 ± 15 pmol/mg of water-soluble (WS) protein). These data provide chemical evidence for increased protein cross-linking during aging and cataract developmentin vivo. This new cross-link may serve as a quantitatively more significant biomarker for assessing the role of lens protein modifications during aging and in the pathogenesis of cataract.

Enhanced dynamics of conformationally heterogeneous T7 bacteriophage lysozyme native state attenuates its stability and activity

2019 ◽  
Vol 476 (3) ◽  
pp. 613-628 ◽  
Author(s):  
Meenakshi Sharma ◽  
Nancy Jaiswal ◽  
Dinesh Kumar ◽  
Krishna Mohan Poluri
Keyword(s):  
Dynamic Properties ◽  
Nmr Relaxation ◽  
Dynamic Features ◽  
Native State ◽  
Structure Dynamics ◽  
Functional Dynamics ◽  
State Ensemble ◽  
The Stability ◽  
Ph Range ◽  
Relationship Of

Abstract Proteins are dynamic in nature and exist in a set of equilibrium conformations on various timescale motions. The flexibility of proteins governs various biological functions, and therefore elucidation of such functional dynamics is essential. In this context, we have studied the structure–dynamics–stability–activity relationship of bacteriophage T7 lysozyme/endolysin (T7L) native-state ensemble in the pH range of 6–8. Our studies established that T7L native state is conformationally heterogeneous, as several residues of its C-terminal half are present in two conformations (major and minor) in the slow exchange time scale of nuclear magnetic resonance (NMR). Structural and dynamic studies suggested that the residues belonging to minor conformations do exhibit native-like structural and dynamic features. Furthermore, the NMR relaxation experiments unraveled that the native state is highly dynamic and the dynamic behavior is regulated by the pH, as the pH 6 conformation exhibited enhanced dynamics compared with pH 7 and 8. The stability measurements and cell-based activity studies on T7L indicated that the native protein at pH 6 is ∼2 kcal less stable and is ∼50% less active than those of pH 7 and 8. A comprehensive analysis of the T7L active site, unfolding initiation sites and the residues with altered dynamics outlined that the attenuation of stability and activity is a resultant of its enhanced dynamic properties, which, in turn, can be attributed to the protonation/deprotonation of its partially buried His residues. Our study on T7L structure–dynamics–activity paradigm could assist in engineering novel amidase-based endolysins with enhanced activity and stability over a broad pH range.

scholarly journals A comparative study to determine the native eye lens protein in the some types of Iraqi vertebrates

2017 ◽  
Vol 14 (2) ◽  
pp. 231-237
Author(s):  
Baghdad Science Journal
Keyword(s):  
Total Concentration ◽  
Spherical Shape ◽  
Average Weight ◽  
Lens Protein ◽  
Tree Frog ◽  
Freshwater Turtles ◽  
Lens Proteins ◽  
Hyla Arborea ◽  
Brown Rat ◽  
Eye Lens Protein

This study showed that the lens in baloot muluki fish Chondrostoma regium is transparent, spherical shape, and solid in textures, while in the tree frog Hyla arborea savignyi, freshwater turtles Clemmys caspia caspia, white–eared bulbul Pycnonotus leucotis and brown rat Rattus norvegicus are transparent, soft and biconvex, it is very soft in white–eared bulbul. There are many significant differences have been recorded between the average weight lens and the total concentration of the protein in the lens all studied animals. Electrical migration process for lens proteins showed that there is one bundle of crystalline –? and one bundle also crystalline–? in all studied species, either crystalline–? may represent one bundle characterized the lens proteins in baloot muluki fish, tree frog, freshwater turtles, and brown rat, while one bundle from crystalline–? appeared in lens proteins of the white – eared bulbul.

The Crystalline Lens of the Eye: An Organismal Microcosm

Physiology ◽  
1986 ◽  
Vol 1 (6) ◽  
pp. 195-199
Author(s):  
PJ Bentley
Keyword(s):  
Old Age ◽  
Blood Supply ◽  
Cell Membranes ◽  
Crystalline Lens ◽  
Toxic Chemicals ◽  
Transparent Medium ◽  
Current Interest ◽  
Lens Proteins ◽  
Naturally Occurring ◽  
High Concentrations

The lens of the eye is transparent due to several special characteristics, including the lack of a blood supply, a tight geometric arrangement of its cells, and high concentrations of special proteins called crystallins, which in solution provide a transparent medium. Opacities of the lens (cataracts), which are especially prevalent in old age, appear to result from damage to lens proteins and cell membranes. Causes of such damage include radiation, sunlight toxic chemicals and drugs, and, of special current interest, naturally occurring oxidants.

scholarly journals A comparative study to determine the nature of the eye lens protein in the two types of birds Iraqi

2015 ◽  
Vol 12 (2) ◽  
pp. 238-241
Author(s):  
Baghdad Science Journal
Keyword(s):  
Comparative Study ◽  
Eye Lens ◽  
Average Weight ◽  
Lens Protein ◽  
Falco Tinnunculus ◽  
Average Amount ◽  
Lens Proteins ◽  
Three Bundles ◽  
Eye Lens Protein

The study showed significant differences between the average weight lens and the average amount protein in the lens between that Kestrel Falco tinnunculus L. and the Collared Dove Streptopelia decaocto F. , also the study electrical migration of lens proteins having one bundle of crystalline –? in Kestrel compared with three bundles in Collared Dove, two bundles of crystalline – ? in both , and crystalline – ? appeared as one bundle in both birds.

New insights into change of lens proteins’ stability with ageing under physiological conditions

2021 ◽  
pp. bjophthalmol-2021-319834
Author(s):  
Chenqi Luo ◽  
Jingjie Xu ◽  
Chenxi Fu ◽  
Ke Yao ◽  
Xiangjun Chen
Keyword(s):  
Protein Stability ◽  
Size Exclusion Chromatography ◽  
Therapeutic Option ◽  
Size Exclusion ◽  
Physiological Status ◽  
Lens Protein ◽  
Lens Proteins ◽  
Physiological Conditions ◽  
Age Related ◽  
Exclusion Chromatography

BackgroundAge-related cataract, which presents as a cloudy lens, is the primary cause of vision impairment worldwide and can cause more than 80% senile blindness. Previous studies mainly explored the profile of lens proteins at a low concentration because of technical limitations, which could not reflect physiological status. This study focuses on protein stability changes with ageing under physiological conditions using a novel equipment, Unchained Labs (Uncle), to evaluate protein thermal stability.MethodsSamples were assessed through Unchained Labs, size-exclusion chromatography, western blot and biophysics approaches including the Thioflavin T, ultraviolet and internal fluorescence.ResultsWith age, the melting temperature value shifted from 67.8°C in the young group to 64.2°C in the aged group. Meanwhile, crystallin may form more isomeric oligomers and easy to be degraded in aged lenses. The spectroscopic and size-exclusion chromatography results show a higher solubility after administrated with lanosterol under the environmental stress.ConclusionWe are the first to explore rabbit lens protein stability changes with ageing using biophysical methods under physiological conditions, and this study can conclude that the structural stability and solubility of lens proteins decrease with ageing. Additionally, lanosterol could aid in resolving protein aggregation, making it a potential therapeutic option for cataracts. So, this study provides cataract models for anti-cataract drug developments

Lens glutathione, lens protein glycation and electrophoretic patterns of lens proteins in STZ induced diabetic rats

1995 ◽  
Vol 12 (5) ◽  
pp. 622-626 ◽  
Author(s):  
Ayşen Yarat ◽  
Zulal Uğuz ◽  
Ali üstünel ◽  
Nesrin Emekli
Keyword(s):  
Diabetic Rats ◽  
Protein Glycation ◽  
Lens Protein ◽  
Lens Proteins ◽  
Electrophoretic Patterns
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