Elastolytic activity of human duodenal contents

Area of Science:

• Biochemistry
• Gastroenterology
• Enzymology

Background:

• Elastolytic activity in human duodenal contents is significant for digestion.
• Previous studies have not fully characterized the enzymes responsible for this activity.

Purpose of the Study:

• To determine the elastolytic activity of human duodenal contents.
• To characterize the enzyme fractions responsible for elastolytic activity.
• To investigate the relationship between elastolytic activity and other pancreatic secretory functions.

Main Methods:

• Utilized a new chromogenic substrate, succinyl-trialanine-p-nitroanilide (Suc-Ala3-NAp), to measure elastolytic activity.
• Employed agar gel electrophoresis and DEAE-Sephadex chromatography for enzyme fractionation.
• Determined molecular weights using Sephadex G-100 chromatography.
• Assessed enzyme kinetics using Michaelis constants.

Main Results:

• Pancreatic stimulation with pancreozymin and secretin significantly increased elastolytic activity in controls compared to subjects with impaired secretory values.
• Two distinct elastolytic fractions were identified: a cathodic fraction cleaving both synthetic and natural substrates, and an anodic fraction cleaving only the synthetic substrate.
• Both fractions exhibited identical molecular weights (24,500) and Michaelis constants (0.45 x 10(-3) M).
• Treatment with trypsin and enterokinase altered the anodic fraction's chromatographic behavior to match the cathodic fraction.

Conclusions:

• Human duodenal contents possess significant elastolytic activity.
• The identified fractions likely represent different activation forms of pancreatic elastase.
• These findings contribute to understanding pancreatic enzyme function and its regulation.