480 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 64 



nuclease, ATPase, DNPase, and hyaluronidase are being used by the 

 biochemist, pharmacologist, and physician. However, these enzymes 

 are not present in all snake venom. In general, Elapidae venoms are 

 rich in cholinesterase and phosphotidase and poor in ATPase. Cro- 

 talidae venoms contain large amounts of hyaluronidase, phosphodies- 

 terase, ribonuclease, and desoxyribonuclease, but little or no cholines- 

 terase. There are species from both families that do not contain 

 L-amino acid oxidase, even though this enzyme has been identified in 

 the venoms of more than 55 species of venomous snakes. While there 

 tends to be a relationship between enzymatic content and the genus of 

 snake, it is not always possible to predict the enzymes present in the 

 venom from data on closely related genera or even species. Not only 

 do different species of the same genus contain different enzymes — or, 

 as in some cases, different amounts of the same enzyme — but even 

 snakes of the same species at different times of the year or under 

 different environmental conditions may exhibit considerable variation 

 in the enzymatic composition of their venoms. Such variations have 

 little relation to the lethality of the whole venom. 



A number of nonenzymatic proteins have been separated from snake 

 venoms, and these appear to be considerably more lethal and in many 

 ways more deleterious than the enzymes. These proteins also differ in 

 number and molecular weight in the venoms of the three families of 

 snakes so far examined. The first of these proteins was isolated from 

 the venom of the tropical rattlesnake, Crotalus terrificus terri-ficus by 

 K. Slotta and H. Fraenkel-Conrat in 1938. The fraction was called 

 "crotoxin" and contained, in addition to the toxic nonenzymatic pro- 

 tein, several enzymes. It was given the tentative formula C1230H1776- 

 O432N328S36 ; it had a molecular weight of 30,000 and was said to be ap- 

 proximately 15 times more lethal than the crude venom. Some years 

 later, J. M. GonQalves obtained three fractions from the same venom, 

 all having specific biological activity : (1) "crotamine," with a molecu- 

 lar weight of 10,000 to 15,000 ; (2) "proteolytic enzyme" ; and (3) "neu- 

 rotoxin," which corresponded to crotoxin in its biological properties. 

 Since the work of these investigators a number of chemical studies have 

 been carried out on the nonenzymatic portion of snake venoms, and 

 studies to date indicate that there may be no less than 6 and perhaps 

 as many as 15 nonenzymatic proteins in most reptile toxins. Some of 

 these fractions, such as "crotactin" and "crotamine," have been identi- 

 fied with specific biological activities; others appear to have several 

 biological activities, while for still others we have not yet found the use 

 to which their properties have been designed. 



The composition of the venoms of marine animals varies consider- 

 ably. Some coelenterate venoms contain: (1) several quaternary 

 ammonium compounds, the most toxic of which is tetramethyl am- 

 monium hydroxide or "tetramine" ; (2) 5-hydroxytryptamine ; (3) 



