488 Annals New York Academy of Sciences 



temperature for polymerization is lowered by addition of polyphosphoric acid 

 to about 70°/ '^^ as well as its contribution to the formation of uracil.^*^ The 

 recent report of Schramm/^ in which is claimed the polymerization of nucleo- 

 tides as earlier proposed in a thermal mode/ occurs under similar conditions. 

 A principal difference is Schramm's use of the ethyl ester of polyphosphoric 

 acid. 



The polyamino acids obtained are referred to as proteinoids because of 

 molecular weif^ht and (jualitative composition, but they have in addition many 

 properties in common with protein.^ '-" 



Two properties of most interest are those of catalytic activity and morpho- 

 genicity. Catalytic activity has been found and studied for the hydrolysis of 

 /»-nitrophenyl acetate. This is an unnatural substrate popularly used in studies 

 by enzyme model chemists.-' This substrate is unstable and hydrolyzes spon- 

 taneously over a large range of pH. Histidine, which has been implicated as 

 part of the active site of many enzymes/" catalyzes this hydrolysis. Simple 

 derivatives of histidine also have this effect and some which are several times 

 as active as histidine have been reported, e.g., carbobenzoxyhistidine.-- Pro- 

 teinoids have been found to be many times as active as that, and in fact 2 of 

 them are more than 15 times as active. 



Of more interest is the fact that the catalytically active proteinoids are in- 

 activated by heat at 100° for 20 minutes in aqueous buffer solution at pH 6.8. 

 This effect has been observed in numerous repetitions and the percentage of 

 inactivation has been found to be greatest for those proteinoids possessing the 

 highest relative activity. 



In an overall view, one interesting relationship involves the fact that cat- 

 alytically powerful macromolecules are formed under almost dry conditions 

 by heating and that this activity is later lost also by heating, but the loss 

 occurs in acjueous solution. The signiiicance of understanding the intimate 

 and subtle effects of water is emphasized by this relationship. Also demon- 

 strated is the fact that very elaborate molecules, approximately as complex as 

 protein molecules, can be produced by a process which, although mechanis- 

 tically complicated, is remarkably simple in operation. 



The kind of morphogenicity observed also depends upon the intrusion of 

 water into the system, under conditions different from those for inducing loss 

 of catalytic activity. Acid proteinoid is typically heated in boiling water or 

 salt solution (1 part of solid to 2000 parts of aqueous phase) for 10 seconds, the 

 hot supernatant decanted and allowed to cool. There result, for each milli- 

 gram of solid, approximately 10^ to lO'^ microspheres of the kind shown in 

 FIGURE 1. The fact that intrusion of water is required for formation of spher- 

 ules demands a relative absence of water from the system before the macro- 

 molecules are organized into supramolecular entities. 



These formed units are of interest as precell models alternative to Oparin's 

 coacervate droplets, also studied as precell models.-^ They and derivatives 

 are of interest also for their morphological similarity to some microfossils-^ 

 and to formed elements found in meteorites.''-^ Interesting differences between 

 microspheres and coacervate droplets are known; for example, both the micro- 

 spheres and bacteria retain their integrity on centrifugation, whereas the 

 coacervate droi)lets coalesce easily.-^ The microspheres also emerge from a 



