Abstract:

Biological proteins have great differences in size, hydrophobicity, pH and relative abundance. Especially, the relative contents of high-abundance proteins and low abundance proteins can reach 11 orders of magnitude or more in blood. However, the contents of proteins which have an important impact on the biological function and have related to major diseases are usually very low in body fluids or tissues. So, it is very meaningful to detect the low abundance proteins in biological samples. A method of large volume recycling injection was developed as a new sample enrichment technology in this study. The low absolute contents of proteins in a sample were improved by increasing the volume of sample, and the enrichment efficiency was also increased with the addition of injection times. With the pork liver protein as an example, under the optimized conditions, the representative contents which were no peaks or little peaks and more peaks with low signals were studied. The contents of peaks at the retention times of 11.38 min and 12.58 min were enriched by 11 time injections of 500 μL each time. The enrichment factors respectively reached 52 and 61 which were closed to theoretical values. This method can be used for the enrichment of biological protein samples.

Key words: enrichment, large volume injection, low abundance, pork liver, proteins, recycling