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Riboflavin photosensitized oxidation...

The Ohio State University.

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Riboflavin photosensitized oxidation of amino acids.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Riboflavin photosensitized oxidation of amino acids./
Author:	Yettella V. Ramesh, Reddy.
Description:	154 p.
Notes:	Adviser: David B. Min.
Contained By:	Dissertation Abstracts International69-08B.
Subject:	Chemistry, Biochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoeng/servlet/advanced?query=3325747
ISBN:	9780549771371

Riboflavin photosensitized oxidation of amino acids.
Yettella V. Ramesh, Reddy.

Riboflavin photosensitized oxidation of amino acids. - 154 p.

Adviser: David B. Min.

Thesis (Ph.D.)--The Ohio State University, 2008.

Milk is an important source of riboflavin and essential amino acids such as phenylalanine, tryptophan, leucine, isoleucine and valine. Riboflavin, a well known photosensitizer could rapidly destroy essential amino acids in milk through oxidation. The effects of Trolox and ascorbic acid on the riboflavin photosensitized oxidation of tryptophan, tyrosine, phenylalanine, methionine, arginine and valine were studied.

ISBN: 9780549771371Subjects--Topical Terms:

1017722
Chemistry, Biochemistry.

Riboflavin photosensitized oxidation of amino acids.
LDR:02839nam 2200301 a 45 001 856968
005 20100709
008 100709s2008 ||||||||||||||||| ||eng d
020 $a 9780549771371
035 $a (UMI)AAI3325747
035 $a AAI3325747
040 $a UMI $c UMI
100 1 $a Yettella V. Ramesh, Reddy. $3 1023867
245 1 0 $a Riboflavin photosensitized oxidation of amino acids.
300 $a 154 p.
500 $a Adviser: David B. Min.
500 $a Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4677.
502 $a Thesis (Ph.D.)--The Ohio State University, 2008.
520 $a Milk is an important source of riboflavin and essential amino acids such as phenylalanine, tryptophan, leucine, isoleucine and valine. Riboflavin, a well known photosensitizer could rapidly destroy essential amino acids in milk through oxidation. The effects of Trolox and ascorbic acid on the riboflavin photosensitized oxidation of tryptophan, tyrosine, phenylalanine, methionine, arginine and valine were studied.
520 $a Riboflavin is a water soluble sensitizer and produces singlet oxygen under light. Aqueous samples with 25 ppm added riboflavin were prepared separately to contain 0, 100, 250, 500, 750 or 1000 ppm of Trolox or ascorbic acid. Samples were stored under light (1000 lux) at 30°C for 10 hours. As the concentration of Trolox and ascorbic increased from 0 to 1000 ppm, the head space oxygen depletion increased. This was due to the oxidation of Trolox and ascorbic acid along with amino acids in the presence of riboflavin. High performance liquid chromatography analysis of the samples indicated that both Trolox and ascorbic acid decreased the degradation of phenylalanine, tryptophan and tyrosine significantly (p<0.05).
520 $a Trolox and ascorbic acid acted as singlet oxygen quenchers and can protect tryptophan and tyrosine. However, the quenching mechanisms are different between Trolox and ascorbic acid. Trolox quenched both singlet oxygen and excited triplet riboflavin under light, where as ascorbic acid quenched singlet oxygen only. The singlet oxygen quenching rate of Trolox in the presence of tryptophan and tyrosine were 1.55 x 107 M-1s-1 and 1.32 x 107 M-1s-1 respectively. The singlet oxygen quenching rate of ascorbic acid in the presence of tryptophan and tyrosine were 1.16 x 107 M-1s-1 and 1.10 x 107 M-1s-1. Singlet oxygen quencher alone could not completely protect tryptophan and tyrosine. Trolox, which is a quencher of both singlet oxygen and excited triplet riboflavin, can better protect tryptophan and tyrosine.
590 $a School code: 0168.
650 4 $a Chemistry, Biochemistry. $3 1017722
650 4 $a Health Sciences, Nutrition. $3 1017801
690 $a 0487
690 $a 0570
710 2 $a The Ohio State University. $3 718944
773 0 $t Dissertation Abstracts International $g 69-08B.
790 $a 0168
790 1 0 $a Min, David B., $e advisor
791 $a Ph.D.
792 $a 2008
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoeng/servlet/advanced?query=3325747