Calcium Binding to Amino Acids and Small Glycine Peptides in

May 9, 2016 - secretion, and precipitation of calcium in the small intestine of the dog. ... absorption of calcium-45 and strontium-89 in the rat. J. ...
0 downloads 0 Views 4MB Size
Subscriber access provided by ORTA DOGU TEKNIK UNIVERSITESI KUTUPHANESI

Article

Calcium binding to amino acids and small glycine peptides in aqueous solution: Towards peptide design for better calcium bioavailability Ning Tang, and Leif H. Skibsted J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.6b01534 • Publication Date (Web): 09 May 2016 Downloaded from http://pubs.acs.org on May 9, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Journal of Agricultural and Food Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 37

Journal of Agricultural and Food Chemistry

1

Calcium Binding to Amino Acids and Small Glycine Peptides in Aqueous Solution: Towards Peptide Design for

2

Better Calcium Bioavailability

3

Ning Tang and Leif H. Skibsted*

4 5

Food Chemistry, Department of Food Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark

6 7

*Corresponding Author:

8

Tel: 45-3533 3221; Fax: 45-3528 3344; E-mail:[email protected]

9 10 11 12 13 14 15 16 17 18 19 20 21

1 ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry

22

Page 2 of 37

Abstract

23

Deprotonation of amino acids as occurring during transfer from stomach to intestines during food digestion was found by

24

comparison of complex formation constants as determined electrochemically for increasing pH to increase calcium binding

25

(i) by a factor of around 6 for the neutral amino acids; (ii) by a factor of around 4 for anions of the acidic amino acids

26

aspartic and glutamic acid; and (iii) by a factor of around 5.5 for basic amino acids. Optimized structures of the 1:1

27

complexes and ∆Hbinding for calcium binding as calculated by Density Functional Theory (DFT) confirmed in all complexes

28

a stronger calcium binding and shorter calcium oxygen bond length in the deprotonated form. In addition, the stronger

29

calcium binding was also accompanied by a binding site shift from carboxylate binding to chelation by α-amino group and

30

carboxylate oxygen for leucine, aspartate, glutamate, alanine and asparagine. For binary amino acid mixtures, calcium

31

binding constant was close to the predicted geometric mean of the individual amino acid binding constants indicating

32

separate binding of calcium to two amino acids when present together in solution. At high pH, corresponding to conditions

33

for calcium absorption, the binding affinity increased along the series: Lys < Arg < Cys < Gln < Gly ~ Ala < Asn < His