35 

 Inhibition studies of S-proteins 

 Enzyme was incubated for 10 min with p-chloromercuri- 

 benzoate or with possible protectants {DTT, cysteine or fS- 

 mercaptoethanol (jSME) } , SDH was assayed at saturating 

 conditions and DQT was assayed at 0.1 xnM DHQ. For 

 prevention experiments, DTT, cysteine, or jSME was added 

 about 10 min before addition of substrates and PCMB, and 

 then rates were determined. For reversal experiments, PCMB 

 was added to enzyme and buffer for 10 min before assay with 

 substrates. After a rate (or no rate) was established, DTT 

 was added to the reaction mix. Concentrations are as stated 

 in Results. 



Antibodies 

 Preparation of specific antibodies 



Antibody preparations were produced by Kel- Farms 

 (Alachua, FL) with repeated injections of purified SP-I over 

 the course of several months until antibody titers, tested 

 by Ouchterlony double diffusion method against SDH, ADH or 

 PAT, were high enough to bleed the rabbits. 

 Purification of specific antibodies 



Antibodies were purified following a BIO-RAD (Rockville 

 Center, NY) procedure, by passing each over Econo-Pac lODG 

 columns for desalting and then passing through DEAE Affi-Gel 

 Blue Econo-Pac lODG columns for serum IgG purification. E. 

 coli strain DH5a lysate was prepared and incubated with the 



