title: Polymerization degrees, molecular weights and protein-binding affinities of condensed tannin fractions from a Leucaena leucocephala hybrid.
abstract: Condensed tannins (CTs) form insoluble complexes with proteins and are able to protect them from degradation, which could lead to rumen bypass proteins. Depending on their degrees of polymerization (DP) and molecular weights, CT fractions vary in their capability to bind proteins. In this study, purified condensed tannins (CTs) from a Leucaena leucocephala hybrid were fractionated into five different molecular weight fractions. The structures of the CT fractions were investigated using 13C-NMR. The DP of the CT fractions were determined using a modified vanillin assay and their molecular weights were determined using Q-TOF LC-MS. The protein-binding affinities of the respective CT fractions were determined using a protein precipitation assay. The DP of the five CT fractions (fractions F1-F5) measured by the vanillin assay in acetic acid ranged from 4.86 to 1.56. The 13C-NMR results showed that the CT fractions possessed monomer unit structural heterogeneity. The number-average molecular weights (Mn) of the different fractions were 1265.8, 1028.6, 652.2, 562.2, and 469.6 for fractions F1, F2, F3, F4, and F5, respectively. The b values representing the CT quantities needed to bind half of the maximum precipitable bovine serum albumin increased with decreasing molecular weight--from fraction F1 to fraction F5 with values of 0.216, 0.295, 0.359, 0.425, and 0.460, respectively. This indicated that higher molecular weight fractions of CTs from L. leucocephala have higher protein-binding affinities than those with lower molecular weights.
authors.affiliation: Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. saminathan_82@yahoo.com.
authors.forename: Mookiah
authors.initials: M
authors.lastname: Saminathan
authors.affiliation: Faculty of Applied Sciences and Computing, Tunku Abdul Rahman University College, 53300 Kuala Lumpur, Malaysia. hytan@acd.tarc.edu.my.
authors.forename: Hui Yin
authors.initials: HY
authors.lastname: Tan
authors.affiliation: Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. norhani@upm.edu.my.
authors.forename: Chin Chin
authors.initials: CC
authors.lastname: Sieo
authors.affiliation: Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. norhani@upm.edu.my.
authors.forename: Norhani
authors.initials: N
authors.lastname: Abdullah
authors.affiliation: Biotechnology Research Institute, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia. michaelw@ums.edu.my.
authors.forename: Clemente Michael Vui Ling
authors.initials: CM
authors.lastname: Wong
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. emilia@upm.edu.my.
authors.forename: Emilia
authors.initials: E
authors.lastname: Abdulmalek
authors.affiliation: Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. ywho@upm.edu.my.
authors.forename: Yin Wan
authors.initials: YW
authors.lastname: Ho
mesh_terms: D007887:Fabaceae / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D044945:Proanthocyanidins / Q000737:chemistry*
chemical_list: D044945:Proanthocyanidins; C013221:proanthocyanidin