MilliporeSigma
  • Home
  • Search Results
  • Lipid binding specificity of bovine α-lactalbumin: a multidimensional approach.

Lipid binding specificity of bovine α-lactalbumin: a multidimensional approach.

Biochimica et biophysica acta (2014-05-08)
Arunima Chaudhuri, Amitabha Chattopadhyay
ABSTRACT

Many soluble proteins are known to interact with membranes in partially disordered states, and the mechanism and relevance of such interactions in cellular processes are beginning to be understood. Bovine α-lactalbumin (BLA) represents an excellent prototype for monitoring membrane interaction due to its conformational plasticity. In this work, we comprehensively monitored the interaction of apo-BLA with zwitterionic and negatively charged membranes utilizing a variety of approaches. We show that BLA preferentially binds to negatively charged membranes at acidic pH with higher binding affinity. This is supported by spectral changes observed with a potential-sensitive membrane probe and fluorescence anisotropy measurements of a hydrophobic probe. Our results show that BLA exhibits a molten globule conformation when bound to negatively charged membranes. We further show, using the parallax approach, that BLA penetrates the interior of negatively charged membranes, and tryptophan residues are localized at the membrane interface. Red edge excitation shift (REES) measurements reveal that the immediate environment of tryptophans in membrane-bound BLA is restricted, and the restriction is dependent on membrane lipid composition. We envision that understanding the mechanism of BLA-membrane interaction would help in bioengineering of α-lactalbumin, and to address the mechanism of tumoricidal and antimicrobial activities of BLA-oleic acid complex.

MATERIALS
Product Number
Brand
Product Description

Supelco
L-Tryptophan, certified reference material, TraceCERT®
Sigma-Aldrich
Oleic acid, natural, FCC
Sigma-Aldrich
Oleic acid, technical grade, 90%
Sigma-Aldrich
Oleic acid, meets analytical specification of Ph, Eur., 65.0-88.0% (GC)
Sigma-Aldrich
L-Tryptophan, BioUltra, ≥99.5% (NT)
Supelco
Oleic acid, analytical standard
Oleic acid, European Pharmacopoeia (EP) Reference Standard
Supelco
Oleic acid, Selectophore, ≥99.0%
Sigma-Aldrich
L-Tryptophan, from non-animal source, meets EP, JP, USP testing specifications, suitable for cell culture, 99.0-101.0%
Sigma-Aldrich
L-Tryptophan, reagent grade, ≥98% (HPLC)
Sigma-Aldrich
Lactalbumin
Sigma-Aldrich
Oleic acid, suitable for cell culture, BioReagent
Sigma-Aldrich
Oleic acid, ≥99% (GC)
Supelco
Tryptophan, Pharmaceutical Secondary Standard; Certified Reference Material
Tryptophan, European Pharmacopoeia (EP) Reference Standard