92 Papers from the Department of Marine Biology. 
hydrolyze histones, protamines, casein, fibrin, and nucleic acid, in addi- 
tion to proteoses and peptones.! Dubois finds that Pholas luciferase 
is digested by trypsin.” 
On the other hand, none of the enzyme preparations tested had any 
action on luciferin. The proteolytic enzymes especially were studied 
with great care and with the result that no digestive action could be 
demonstrated. In one experiment not recorded in the table luciferin 
was mixed with a pancreatin preparation having active proteolytic 
power and kept at 38° for 4 days without digesting the luciferin. 
Erepsin also had no digestive action after 4 days at 38°. Merck’s pan- 
creatin (without toluol) had no digestive action after 8 days at 38° C. 
Dried, powdered cypridinze were mixed with Merck’s pancreatin and 
toluol and kept at 38° C. for 8 days. This digest was found to con- 
tain no luciferase but abundant luciferin. There is no doubt of the 
non-digestibility of the latter. As already mentioned, these digests 
must be carried out in absence of oxygen; otherwise the luciferin under- 
goes spontaneous oxidation and disappears, apart from any enzyme 
action. As we have seen, this oxidation involves no fundamental 
alteration of the luciferin molecule and the product (oxyluciferin) can 
be again reduced to luciferin. The oxyluciferin (like luciferin itself) is 
also undigested after 4 days’ action of a pancreatin solution at 38° C. 
As all proteins except the racemized proteins and certain very insoluble 
albuminoids (elastin and keratin) are digested by trypsin, these experi- 
ments would seem to indicate that luciferin is not protein. However, 
this question will be again considered in the summary. 
SALTING OUT. 
If crude luciferase solution is saturated with crystals of NaCl at 
20° C. no precipitate forms, but only a slight turbidity appears. The 
solution filters turbid and luciferase is found unharmed in the filtrate. 
Saturation with NaCl is a good method of preserving luciferase from 
the growth of molds and bacteria. 
One-half saturation with MgSO, also produces a slight turbidity and 
luciferase is found unharmed in the filtrate. Complete saturation 
with MgSO, produces a fine precipitate, again dissolving in water 
which contains considerable luciferase. The opalescent filtrate also 
contains some luciferase, so that saturated MgSO, precipitates lucif- 
erase partially but not completely. 
One-half saturation with (NH,4)2SO, produces a precipitate which con- 
tains very little luciferase after washing with half-saturated (NH4)2SOx. 
Most of the luciferase is found in the filtrate. On saturation with 
(NH,).:SO, an abdundant precipitate forms and no luciferase remains 
1 Oppenheimer’s Handb. d. Biochem., i, 554. 
2 Dubois, R., Ann. Soc. Linn. de Lyons, 1914, lxi, 161. 
