Possible reactions of 1,2-naphthaquinone in the eye

1967 ◽  
Vol 102 (3) ◽  
pp. 853-863 ◽  
Author(s):  
R.R. Jancis ◽  
Pirie Antoinette
Keyword(s):  
Amino Acids ◽  
Ascorbic Acid ◽  
Aqueous Humour ◽  
Thiol Group ◽  
Amino Group ◽  
Reaction Products ◽  
Protein Thiol ◽  
Alpha Crystallin ◽  
Group 4 ◽  
Normal Lens

1. Reactions of 1,2-naphthaquinone with amino acids, glutathione and proteins of the lens have been studied in connexion with investigations of naphthalene-induced cataract. 2. Cysteine reacts probably through its amino group with 1,2-naphthaquinone to form either purple or brown compounds with characteristic absorption spectra. 3. Glutathione reacts with 1,2-naphthaquinone through its thiol group. 4. Spectroscopic evidence suggests that 1,2-naphthaquinone reacts with the amino group of amino acids. This reaction may take place in the aqueous humour. 5. The proteins of lens react with 1,2-naphthaquinone to form brown compounds. 6. There is loss of protein thiol in this reaction and the products are less easily digestible by pancreatin than normal lens proteins. 7. The compound of alpha-crystallin and 1,2-naphthaquinone is soluble at neutrality, but the compounds of beta-crystallins and of gamma-crystallins are largely insoluble. 8. The brown reaction products of glutathione or cysteine with 1,2-naphthaquinone catalyse the oxidation of ascorbic acid in the same way as 1,2-naphthaquinone itself. 9. These results are discussed in relation to naphthalene-induced cataract.

scholarly journals o-Quinones formed in plant extracts. Their reactions with amino acids and peptides

1969 ◽  
Vol 112 (5) ◽  
pp. 609-616 ◽  
Author(s):  
W. S. Pierpoint
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plant Extracts ◽  
Thiol Group ◽  
Amino Group ◽  
Amino Groups ◽  
Terminal Amino Acid ◽  
Secondary Reactions ◽  
Terminal Amino ◽  
Group 5

1. The reactions of amino acids and peptides with the o-quinones produced by the enzymic oxidation of chlorogenic acid and caffeic acid have been studied manometrically and spectrophotometrically. 2. Amino acids, except lysine and cysteine, react primarily through their α-amino groups to give red or brown products. These reactions, which compete with the polymerization of the quinones, are followed by secondary reactions that may absorb oxygen and give products with other colours. 3. The ∈-amino group of lysine reacts with the o-quinones in a similar way. The thiol group of cysteine reacts with the quinones, without absorbing oxygen, giving colourless products. 4. Peptides containing cysteine react with the o-quinones through their thiol group. 5. Other peptides, such as glycyl-leucine and leucylglycine, react primarily through their α-amino group and the overall reaction resembles that of the N-terminal amino acid except that it is quicker. 6. With some peptides, the secondary reactions differ from those that occur between the o-quinones and the N-terminal amino acids. The colours produced from carnosine resemble those produced from histidine rather than those from β-alanine, and the reactions of prolylalanine with o-quinones are more complex than those of proline.

scholarly journals The measurement of amino groups in proteins and peptides

1971 ◽  
Vol 124 (3) ◽  
pp. 581-590 ◽  
Author(s):  
R Fields
Keyword(s):  
Amino Acids ◽  
Room Temperature ◽  
Thiol Group ◽  
Amino Group ◽  
Thiol Groups ◽  
Amino Groups ◽  
Model Compounds ◽  
Time Required ◽  
Short Time ◽  
Proteins And Peptides

A technique is examined for determining amino groups with 2,4,6-trinitrobenzenesulphonic acid, in which the extinction at 420nm of sulphite complexes of the trinitrophenylated amino groups is measured. The sensitivity of the method is 5–200nmol of amino group. The method is especially suitable for checking the extent of blocking or unblocking of amino groups in proteins and peptides, owing to the short time required for reaction (5min at room temperature). The reaction of the reagent with thiol groups has been studied and was found to proceed 30–50 times faster than with ∈-amino groups of model compounds. The ∈420 of a trinitrophenylated thiol group was found to be 2250m-1·cm-1. The reaction with several amino acids, peptides and proteins is presented. The ∈420 of a typical α-amino group was found to be 22000m-1·cm-1 and that of an ∈-amino group, 19200m-1·cm-1. Difficulties inherent in the analysis of constituent amino group reactions in proteins are discussed.

The Kinetics of Inhibition of the Action of Thrombin by the Fibrinopeptides Formed during the Clotting of Fibrinogen

1966 ◽  
Vol 16 (01/02) ◽  
pp. 277-295 ◽  
Author(s):  
A Silver ◽  
M Murray
Keyword(s):  
Amino Acids ◽  
Competitive Inhibition ◽  
Amorphous Material ◽  
Peptide Bond ◽  
Initial Reaction ◽  
Reaction Products ◽  
Coagulation Mechanism ◽  
Kinetics Of ◽  
Kinetics Of Inhibition ◽  
Burk Plot

SummaryVarious investigators have separated the coagulation products formed when fibrinogen is clotted with thrombin and identified fibrinopeptides A and B. Two other peaks are observed in the chromatogram of the products of coagulation, but these have mostly been dismissed by other workers. They have been identified by us as amino acids, smaller peptides and amorphous material (37). We have re-chromatographed these peaks and identified several amino acids. In a closed system of fibrinogen and thrombin, the only reaction products should be fibrin and peptide A and peptide B. This reasoning has come about because thrombin has been reported to be specific for the glycyl-arginyl peptide bond. It is suggested that thrombin also breaks other peptide linkages and the Peptide A and Peptide B are attacked by thrombin to yield proteolytic products. Thrombin is therefore probably not specific for the glycyl-arginyl bond but will react on other linkages as well.If the aforementioned is correct then the fibrinopeptides A and B would cause an inhibition with the coagulation mechanism itself. We have shown that an inhibition does occur. We suggest that there is an autoinhibition to the clotting mechanism that might be a control mechanism in the human body.The experiment was designed for coagulation to occur under controlled conditions of temperature and time. Purified reactants were used. We assembled an apparatus to record visually the speed of the initial reaction, the rate of the reaction, and the density of the final clot formed after a specific time.The figures we derived made available to us data whereby we could calculate and plot the information to show the mechanism and suggest that such an inhibition does exist and also further suggest that it might be competitive.In order to prove true competitive inhibition it is necessary to fulfill the criteria of the Lineweaver-Burk plot. This has been done. We have also satisfied other criteria of Dixon (29) and Bergman (31) that suggest true competitive inhibition.

Chemically Selective Reactions in Confined Spaces in Hybrid Aerogels

2005 ◽  
Vol 899 ◽  
Author(s):  
Xipeng Liu ◽  
Chunhua Yao ◽  
William M Risen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Metal Ions ◽  
Chemical Reactions ◽  
Reaction Products ◽  
Spatial Confinement ◽  
Confined Spaces ◽  
Hybrid Silica ◽  
Hybrid Aerogels ◽  
Chemically Selective

AbstractBy employing novel hybrid silica/functional polymer aerogels, control of the course of chemical reactions between reactants confined inside of the aerogels with reactants whose access to the confinement domain is controlled by diffusion has been explored. Thus, monolithic silica/biopolymer hybrid aerogels have been synthesized with coordinated metal ions that can react with amino acids, such as L-cysteine, that are provided externally in a surrounding solution. Metal ions, such as Au(III), that can react in solution with the amino acid to produce one set of products under a given set of stoichiometric or concentration conditions, and a different set of products under a second set of conditions, were selected for incorporation into the aerogel. It was discovered that the course of the reaction can be changed by spatial confinement of the reaction domain in the aerogel. For example, in the case of Au(III) and L-cysteine, the Au(III) ions are confined in nanoscale domains, and when they are reacted with the amino acid, the nature of the reaction products is controlled by diffusion of the L-cysteine into the domains. Exploration of these and related phenomena will be presented.

scholarly journals Free Amino Acids in the Human Aqueous Humour

1954 ◽  
Vol 38 (6) ◽  
pp. 357-363 ◽  
Author(s):  
C. Wunderly ◽  
B. Cagianut
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Aqueous Humour

Special transport and neurological significance of two amino acids in a configuration conventionally designated as D.

1994 ◽  
Vol 196 (1) ◽  
pp. 297-305 ◽  
Author(s):  
H N Christensen ◽  
A A Greene ◽  
D K Kakuda ◽  
C L MacLeod
Keyword(s):  
Amino Acids ◽  
Receptor Site ◽  
Amino Group ◽  
Carboxylate Group ◽  
Gamma Aminobutyric Acid ◽  
Imino Group ◽  
Group A ◽  
The Central Nervous System ◽  
Lower Homolog ◽  
Alpha Amino Acid

We point out an ability of certain amino acids to be recognized at a biological receptor site as though their amino group bore, instead of an alpha relationship to a carboxylate group, a beta, gamma or delta relationship to the same or a second carboxylate group. For aspartate, the unbalanced position of its amino group between a pair of carboxylates allows its occasional biorecognition as a beta-rather than as an alpha-amino acid, whereas for proline and its homologs, their cyclic arrangement may allow the imino group, without its being replicated, to be sensed analogously as falling at either of two distances from the single carboxylate group. The greater separation might allow proline to be seen as biologically analogous to gamma-aminobutyric acid. This more remote positioning of the imino group would allow the D-form of both amino acids to present its amino group in the orientation characteristic of the natural L-form. The dual modes of recognition should accordingly be signalled by what appears to be low stereospecificity, actually due to a distinction in the enantiorecognition of the two isomers. Competing recognition for transport between their respective D- and L-forms, although it does not prove that phenomenon, has been shown for proline and, significantly, even more strongly for its lower homolog, 2-azetidine carboxylate. Such indications have so far revealed themselves rather inconspicuously for the central nervous system binding of proline, reviewed here as a possible feature of a role suspected for proline in neurotransmission.

NODULATION RESPONSES OF TWO NEAR ISOGENIC LINES OF THE SOYBEAN

1957 ◽  
Vol 3 (2) ◽  
pp. 113-123 ◽  
Author(s):  
Francis E. Clark
Keyword(s):  
Amino Acids ◽  
Ascorbic Acid ◽  
Nutrient Solution ◽  
The Other ◽  
Negative Response ◽  
Sand Culture ◽  
Near Isogenic Lines ◽  
Soybean Line ◽  
Sand Cultures ◽  
Different Soils

Nodulation responses and certain other characteristics of a mutant soybean line highly recalcitrant to nodulation were compared with those of a nodulating sister line. Roots of the two lines were found to harbor equal numbers of rhizobia. Stem graftings to provide top growths of one line on roots of the other failed to alter the distinctive nodulation responses of rootstocks. Ascorbic acid contents in the two lines were identical, both in the tops and in the roots, although contents in tops greatly exceeded those found in roots. Chromatographic studies on the amino acids in seed hydrolyzates and in alcoholic extracts of seedlings showed no differences between the two lines either in kind or quantities of amino acids. In a survey of stock rhizobia for cultures effective on the nonnodulating line, bacteria were discovered which formed nodules on such soybeans growing in sand and nutrient solution. Isolates from these nodules again yielded effective nodulation on plants in sand culture, but gave no nodulation whatsoever on plants growing in soil. This negative response was confirmed in three different soils. Admixtures of soil and of miscellaneous materials with sand were employed to alter nodulation responses from those shown in sand cultures.

The Composition of the Seminal Plasma of Balanus Balanus

1962 ◽  
Vol 39 (3) ◽  
pp. 345-352
Author(s):  
H. BARNES
Keyword(s):  
Amino Acids ◽  
Ascorbic Acid ◽  
Amino Acid ◽  
Seminal Plasma ◽  
Free Amino ◽  
Reducing Sugars ◽  
Sea Water ◽  
Protective Action ◽  
Inorganic Ions ◽  
Chemical Analyses

1. The results of some chemical analyses for inorganic and organic constituents of the seminal plasma of Balanus balanus are presented. 2. The inorganic ions show a cation deficit of 178 m-equiv./l., which is probably made up by free amino-acids. 3. Cystine is a prominent amino acid present. 4. Potassium and calcium are present in excess of their quantities in sea water. 5. Reducing sugars, compared with the amount found in sea-urchin spermatozoa, are found in moderate quantities, 1 mg./ml. 6. Phosphorus of all kinds is present in only small quantities (total of o.14 mg./ml.). 7. Some phosphatases are present. 8. There are 21 /µg./ml. of ascorbic acid; the function of this is discussed in relation to its possible contribution to the protective action against the poisoning of -SH groups by thiol-reactive agents.

Sign in / Sign up

Export Citation Format

Share Document