Isoelectric focusing in immobilized pH gradients with carrier ampholytes added for high‐resolution phenotyping of bovine β‐lactoglobulins: Characterization of a new genetic variant

Publisher Website
Google Scholar
Abstract
The genetic variants of bovine β‐lactoglobulin (β‐lg) from the “Murnau‐Werdenfelser” breed were analyzed in three different isoelectric focusing (IEF) systems. While carrier ampholyte IEF with a pH gradient of 0.2 pH/cm did not resolve the new variant W from the B variant and IEF in immobilized pH gradients (IPG) with 0.1 pH/cm only partially resolved it, adequate separation was achieved with IPG‐IEF in a pH 5.25‐pH 5.7 gradient, in presence of 0.8 % w/v carrier ampholytes, both over a 10 and 17 cm separation distance. Apparent isoelectric points (pI's) and genetic frequencies (f) were as follows: β‐lg A, pI = 5.370,f = 0.364; β‐lg B, pI = 5.485,f = 0.480; β‐lg W, pI = 5.492,f = 0.076; and β‐lg D, pI = 5.610,f = 0.080. The small difference of Δ pI = 0.007 between β‐lg B and β‐lg W respectively, seems to originate from a “silent” substitution of neutral amino acid residues as compared to the larger Δ pI's of the other genetic variants of β‐lg, which result from substitution of charged amino acids.