Proteins still remain the subject of interest from the day it was discovered. The first proteins of the body to be studied widely ever includes Albumin, Haemoglobin, and Fibrin. Of these, Serum Albumin remains a model protein for physiological studies for many years. Some examples of albumins are: Human Serum Albumin (HSA), Bovine Serum Albumin (BSA), Equine Serum Albumin (ESA), Rat Serum Albumin (RTSA), Mouse Serum Album (MSA), Pig Serum Albumin (PSA), Sheep Serum Albumin (OSA), Frog Serum Albumin (XSA), Rabbit Serum Albumin (RSA) and Salmon Serum Albumin (SSA).
Of all the serum albumins, ESA (Ho et al., 1993), and HSA (Carter et al., 1989; Carter and He, 1990; He and Carter, 1992) has been crystallized so far and their 3D structures have been determined. Though BSA exhibited 80% sequence homology with HSA, all previous attempts to crystallize it have failed. According to RCSB Protein Data Bank (PDB), no other 3-D structure of Serum Albumins has been published until the end of 2011.
But very recently another step has taken forward in the world of protein crystallography by the group Majorek et al. who have succeeded in determining the crystal structure of Bovine Serum Albumin (BSA) and Rabbit Serum Albumin (RSA) with X ray crystallography with a resolution of 2.7 Å (PDB ID-3V03) and 2.27 Å (PDB ID-3V09) respectively. The crystallographic data have been submitted in the month of January but the journal is yet to be published.