A protein biosensor for lactate

Blood lactate is a clinically valuable diagnostic indicator. In this prelim inary report we describe a protein biosensor for L-lactate based on beef he art lactate dehydrogenase (LDH). LDH was noncovalently labeled with 8-anili no-1-naphthalene sulfonic acid (ANS). The ANS-labeled LDH displayed an appr oximately 40% decrease in emission intensity upon binding lactate. This dec rease can be used to measure the lactate concentration. The ANS-labeled LDH was further utilized in a new sensing format, polarization sensing, which is suitable for miniaturization to a point-of-care lactate monitor. However , temporal instability of beef heart LDH indicates the need for further pro tein engineering prior to development of a more robust lactatesensing prote in. (C) 2000 Academic Press.