Butyrate-binding protein from rat and mouse liver

Area of Science:

• Biochemistry
• Molecular Biology
• Hepatology

Background:

• Butyrate is a short-chain fatty acid with significant physiological roles.
• Cellular mechanisms for butyrate binding and transport are not fully elucidated.
• Previous studies identified fatty acid-binding proteins but lacked specificity for butyrate.

Purpose of the Study:

• To identify and characterize a novel protein component that specifically binds butyrate in liver tissue.
• To determine the biochemical properties and binding characteristics of this butyrate binding protein (BBP).
• To differentiate BBP from previously known fatty acid-binding proteins.

Main Methods:

• Isolation and partial purification of BBP from rat and mouse liver cytosolic fractions.
• Characterization of BBP's protein nature using heat and protease sensitivity assays.
• Determination of BBP's molecular size (7.6S native, 45,000–48,000 Da subunits via SDS-PAGE).
• Quantification of butyrate binding affinity using dissociation constant (Kd = 2.22 x 10^-6 M).
• Purification of BBP using CM-cellulose and hydroxylapatite column chromatography.

Main Results:

• A novel butyrate binding protein (BBP) was identified in the cytosolic fraction of rat and mouse liver.
• BBP exhibits typical protein properties, including sensitivity to heat and proteases.
• The native molecular size of BBP is 7.6S, dissociating into 45,000–48,000 Da subunits under SDS treatment.
• BBP demonstrates a high affinity for butyrate, with a dissociation constant of 2.22 x 10^-6 M.
• A 30-fold purification of BBP was achieved, confirming its distinct nature.

Conclusions:

• A novel, specific butyrate binding protein (BBP) exists in the liver cytosol.
• BBP possesses distinct molecular and binding properties differentiating it from other known fatty acid-binding proteins.
• This discovery provides a new molecular target for understanding butyrate metabolism and transport in the liver.