Protein that precipitates on heating to 45 C and redissolves on boiling is

Bence-Jones&; Protein An abnormal protein occurs in blood and urine of people suffering from a disease called multiple myeloma (a plasma cell tumour). Defined as monoclonal light chains present in the urine of patients with paraproteinaemic states. Either monoclonal `k&; or `l&; light chains are excreted in significant amounts in about 50 percent cases of multiple myeloma. It has a molecular weight 45000 and has sedimentation coefficient of 3.5 S. Sometimes the chains excreted may be a `dimer&; of L-chains. Identification--Heat Test * The protein is identified easily in urine by a simple Heat Test. On heating the urine 50 to 60oC, Bence-Jones&; proteins are precipitated, but when heated fuher it dissolves again. Reverse occurs upon cooling. * Best detected by zone electrophoresis and immunoelectrophoresis of concentrated urineRef: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 104