Carbonic anhydrase preparations from human erythrocytes contain at least three distinct molecular forms of the enzyme (l-4), two of which-denoted here as carbonic anhydrases B and C-have been studied in detail. They differ widely in specific activity, and also in their isoelectric points (1, 4), their amino acid composition (4-6), and their chromatographic behavior (3,4). Earlier studies on the...

iii GENERAL INTRODUCTION 1 PART 1. DECIPHERING PROTEOLYTIC PROCESSING OF PERIPLASMIC CARBONIC ANHYDRASE 1(CAH1) 9

The prototype of the gamma-class of carbonic anhydrase has been characterized from the methanogenic archaeon Methanosarcina thermophila. Previously reported kinetic studies of the gamma-class carbonic anhydrase are consistent with this enzyme having a reaction mechanism similar to that of the mammalian alpha-class carbonic anhydrase. However, the overall folds of these two enzymes are dissimila...

Mosquito larvae use a digestive strategy that is relatively rare in nature. The anterior half of the larval mosquito midgut has a luminal pH that ranges between 10.5 and 11.5. Most other organisms, both large and small, initiate digestion in an acid medium. The relative uniqueness of the highly alkaline digestive strategy has been a long-standing research focus in larval lepidopterans. More rec...

The larval mosquito midgut exhibits one of the highest pH values known in a biological system. While the pH inside the posterior midgut and gastric caeca ranges between 7.0 and 8.0, the pH inside the anterior midgut is close to 11.0. Alkalization is likely to involve bicarbonate/carbonate ions. These ions are produced in vivo by the enzymatic action of carbonic anhydrase. The purpose of this st...