The critically acclaimed laboratory standard for more than forty years, Methods in Enzymology is one of the most highly respected publications i n the field of biochemistry. Since 1955, each volume has been eagerly aw aited, frequently consulted, and praised by researchers and reviewers al ike. Now with more than 300 volumes, all of them still in print, the ser ies contains much material still relevant today; truly an essential publ ication for researchers in all fields of life sciences. This volume focu ses on methods related to allosteric enzymes and receptors, including fl uorescent proves, spectroscopic methods and quantitative analysis as wel l as on cooperativity in protein folding. NMR and mass spectrometry meth ods are discussed.