Substrate Report for: 2,3-Dimercapto-1-propanol-tributyrate

We have compared responsiveness of serum lipase and amylase activity to the pancreatic exocrine stimulation with cerulein and secretin (CS test) in normal subjects and patients with pancreas-related and other diseases. The lipase and amylase activities were measured by a sensitive colorimetric method, the BALB-DTNB method and the Caraway method, respectively. The percentage of positive lipase and amylase response cases was as follows: confirmed chronic pancreatitis (N = 22), 27 and 14%; suspected chronic pancreatitis (N = 37), 46 and 32%; pancreatic cancer (N = 16), 44 and 25%; biliary tract diseases (N = 11), 14 and 14%; miscellaneous (N = 11), 0 and 18%; normal subjects (N = 13), and partial pancreatectomy (N = 5), 0 and 0%, respectively. The serum lipase response cannot be regarded as specific for pancreatic diseases because the lipase response cases were found in biliary tract diseases as well. However, in view of frequent, fast, and intense responsiveness to the CS test, the serum lipase activity measured by the BALB-DTNB method may be more useful than the serum amylase as an auxiliary diagnostic aid for suspected pancreatitis which might develop into confirmed chronic pancreatitis or cancer of the head or body of the pancreas.

We successfully adapted the dimercaprol (BAL) tributyrate-5,5'-dithiobis(2-nitrobenzoic acid) method (J. Biochem. 81: 361, 1977) for assay of lipase in human serum to a discrete analyzer (the TBA 880) (I) or a continuous-flow analyzer (AutoAnalyzer, Type II) (II). In both, BAL-tributyrate is used as substrate, in combination with serum esterase inhibitors and a chromogenic reagent for the SH group of the liberated BAL. Serum lipase activities of patients with pancreatic diseases, measured at 90 or 40 samples per hour by I or II, respectively, correlated well with those measured by the corresponding manual method or by Kaplan's radioassay (Anal. Biochem. 33: 213, 1970). The correlation coefficients were all greater than 0.95, and the coefficients of variation were less than 8%, showing the practical usefulness of these procedures.

Very low levels of lipase can easily be measured by a new serum lipase assay method (the BALB-DTNB method), using BAL-tributyrate (BALB) as a substrate, 5,5'-dithiobis(2-nitrobenzoic acid) as a chromogenic SH reagent, phenylmethylsulfonylfluoride as an inhibitor of esterases and sodium dodecyl sulfate as a surfactant. The BALB-DTNB method has a higher sensitivity than the conventional serum lipase assay methods, and proved useful for analyzing the properties of serum lipases in combination with gel-filtration on a Sephacryl S 200 column and isoelectrofocusing in an Ampholine column. Serum samples containing high levels of lipases from patients with pancreatic diseases or patients in whom the pancreatic exocrine gland had been stimulated by injecting caerulein and secretin were analyzed by these methods. The lipolytic profiles obtained indicated the presence of a lipase with an estimated molecular weight of 46,000 and isoelectric points of 7.4, 6.8, or/and 6.4. A lipase with properties similar to those of the serum lipase was found to be present in human pancreatic juice.

Acne is one of the most common dermatological conditions, but the details of its pathology are unclear, and current management regimens often have adverse effects. Cutibacterium acnes is known as a major acne-associated bacterium that derives energy from lipase-mediated sebum lipid degradation. C. acnes is commensal, but lipase activity has been observed to differ among C. acnes types. For example, higher populations of the type IA strains are present in acne lesions with higher lipase activity. In the present study, we examined a conserved lipase in type IB and II, but truncated in type IA C. acnes strains. Closed, blocked, and open structures of C. acnes ATCC11828 lipases were elucidated by X-ray crystallography at 1.6-2.4 A. The closed crystal structure, which is the most common form in aqueous solution, revealed that hydrophobic lid domain shields the active site. By comparing closed, blocked, and open structures, we found that the lid domain-opening mechanisms of C. acnes lipases involve the lid-opening residues, Phe- 179 and Phe-211. To the best of our knowledge, this is the first structure-function study of C. acnes lipases, which may help shed light on the mechanisms involved in acne development and may aid in future drug design.

The present work describes a colorimetric microplate assay for lipase activity based on the reaction between 5,5'-dithiobis(2-nitro benzoic acid) (DTNB) and the hydrolysis product of 2,3-dimercapto-1-propanol tributyrate (DMPTB). Reaction mixtures containing DTNB, DMPTB, and lipase were prepared in microplate wells, and the absorbance at 405nm was recorded after incubation at 37 degrees C for 30 min. A linear relationship was obtained in the range of 0.1-1 U of lipase activity by this method. The reaction conditions were also optimized for the range of 0.01-0.1 U or 1-10 U. When assaying crude tissue extracts, the reaction of DTNB with non-specific reducing agents created a major source of error. However, this error was corrected by the use of blank samples that did not contain DMPTB.

The British antilewisite butyrate-dithionitrobenzoate (BALB-DTNB) spectrophotometric serum lipase assay was evaluated for precision, accuracy, and diagnostic usefulness in analyzing canine sera. Sera samples from clinically healthy dogs, dogs with experimentally induced pancreatitis, and dogs with spontaneous pancreatitis were analyzed. A titrimetric method of serum lipase determination was used for comparison. Although the BALB-DTNB method was not found to be precise or accurate for determining the lipase activity of canine serum samples, it seemed to be at least as diagnostically useful as the titrimetric procedure. The small sample size requirement and the speed of analysis of the BALB-DTNB procedure are advantages of this method over the titrimetric method, and thus, its use in place of the titrimetric method is justified. A laboratory reference range of 3 to 37 IU/L was determined for canine serum.

We have compared responsiveness of serum lipase and amylase activity to the pancreatic exocrine stimulation with cerulein and secretin (CS test) in normal subjects and patients with pancreas-related and other diseases. The lipase and amylase activities were measured by a sensitive colorimetric method, the BALB-DTNB method and the Caraway method, respectively. The percentage of positive lipase and amylase response cases was as follows: confirmed chronic pancreatitis (N = 22), 27 and 14%; suspected chronic pancreatitis (N = 37), 46 and 32%; pancreatic cancer (N = 16), 44 and 25%; biliary tract diseases (N = 11), 14 and 14%; miscellaneous (N = 11), 0 and 18%; normal subjects (N = 13), and partial pancreatectomy (N = 5), 0 and 0%, respectively. The serum lipase response cannot be regarded as specific for pancreatic diseases because the lipase response cases were found in biliary tract diseases as well. However, in view of frequent, fast, and intense responsiveness to the CS test, the serum lipase activity measured by the BALB-DTNB method may be more useful than the serum amylase as an auxiliary diagnostic aid for suspected pancreatitis which might develop into confirmed chronic pancreatitis or cancer of the head or body of the pancreas.

We successfully adapted the dimercaprol (BAL) tributyrate-5,5'-dithiobis(2-nitrobenzoic acid) method (J. Biochem. 81: 361, 1977) for assay of lipase in human serum to a discrete analyzer (the TBA 880) (I) or a continuous-flow analyzer (AutoAnalyzer, Type II) (II). In both, BAL-tributyrate is used as substrate, in combination with serum esterase inhibitors and a chromogenic reagent for the SH group of the liberated BAL. Serum lipase activities of patients with pancreatic diseases, measured at 90 or 40 samples per hour by I or II, respectively, correlated well with those measured by the corresponding manual method or by Kaplan's radioassay (Anal. Biochem. 33: 213, 1970). The correlation coefficients were all greater than 0.95, and the coefficients of variation were less than 8%, showing the practical usefulness of these procedures.

Very low levels of lipase can easily be measured by a new serum lipase assay method (the BALB-DTNB method), using BAL-tributyrate (BALB) as a substrate, 5,5'-dithiobis(2-nitrobenzoic acid) as a chromogenic SH reagent, phenylmethylsulfonylfluoride as an inhibitor of esterases and sodium dodecyl sulfate as a surfactant. The BALB-DTNB method has a higher sensitivity than the conventional serum lipase assay methods, and proved useful for analyzing the properties of serum lipases in combination with gel-filtration on a Sephacryl S 200 column and isoelectrofocusing in an Ampholine column. Serum samples containing high levels of lipases from patients with pancreatic diseases or patients in whom the pancreatic exocrine gland had been stimulated by injecting caerulein and secretin were analyzed by these methods. The lipolytic profiles obtained indicated the presence of a lipase with an estimated molecular weight of 46,000 and isoelectric points of 7.4, 6.8, or/and 6.4. A lipase with properties similar to those of the serum lipase was found to be present in human pancreatic juice.