LIPASE 89 



Co., and are known as "Tweens." Tween 40 and Tween 60, employed 

 by Gomori, are described by Atlas Powder Co. as "sorbitan mono- 

 palmitate polyoxyalkylene derivative" and "sorbitan monostearate 

 polyoxyalkylene derivative," respectively. Gomori states that these 

 substrates were found to be hydrolyzed by pancreatic lipase at a 

 rate about half that of olive oil. In the presence of 0.2% sodium 

 taurocholate an intensification of the reaction in pancreatic tissue 

 was noted, while in all other tissues, enzyme inhibition was observed. 

 In a later publication Gomori (1946a) reported that "Product 81" 

 of Otiyx Oil and Chemical Co. could also serve as a lipase substrate 

 for histochemical purposes. This compound is a stearic acid ester 

 of "comparatively short-chained polyglycols." The only shortcoming 

 observed by Gomori to the use of these substrates is an occasional 

 failure to obtain proper counterstaining with hematoxylin, especially 

 after use of the "Tweens" and more rarely with "Product 81." The 

 method as finally given by Gomori (1946c) will be described. 



Gomori Revised Method for Lipase 



SPECIAL REAGENTS 



5% Acetylcellulose (Eastman's No. 4644) in acetone. 



1-2% Lead Nitrate. 



Ammonium Sulfide- Solution. A few drops of yellow ammonium 

 sulfide soln. to a Coplin jar of distilled water. 



Substrate Medium. Stock solution I: combine 150 ml. glycerol, 

 60 ml. of 10% calcium chloride, 50 ml. M/2 maleate buffer pH 

 7 to 7.4 (dissolve 5.8 g. maleic acid in 94 ml. of 4% sodium 

 hydroxide and 6 ml. water), and distilled water to make 1000 ml. 

 Stock solution II: 5% Tween 40 or 60 or "Product 81." Add 

 merthiolate to 0.02% in each stock soln. and store in refrigerator; 

 the solns. may be used for many months. Before use, add 2 ml. 

 stock soln. II to 50 ml. stock soln. I. 



PROCEDURE 



1-6. Same as for alkaline phosphatase (pages 79 and 80). 



7. Incubate the sections in the substrate medium for 6-12 hr. 

 at 37°. 



8. Rinse with distilled water and transfer to the lead nitrate 

 soln. for 10 min. 



