Conversion between renin and high-molecular-weight renin in the dog

Area of Science:

• Biochemistry
• Renal Physiology

Background:

• Renin, a key enzyme in the renin-angiotensin system, exists in different molecular forms.
• Understanding renin's molecular weight variations is crucial for comprehending its regulation and activity.

Purpose of the Study:

• To investigate the different molecular forms of renin in dog kidney.
• To elucidate the conversion process and storage mechanism of renin.

Main Methods:

• Molecular weight determination of renin using gel filtration or SDS-PAGE.
• Analysis of renin conversion in kidney homogenates and isolated granules.
• Investigation of the role of thiol-reactive substances in renin conversion.

Main Results:

• Two renin forms with molecular weights of 43,000 and 60,000 were identified in dog kidney.
• Renin conversion between these forms was reversible at neutral pH.
• Renin in kidney-cortex homogenate (43,000 MW) converted to a high-molecular-weight form (60,000 MW) in the presence of thiol-reactive substances.
• Stored renin in granules maintained its normal size (43,000 MW) irrespective of thiol-reactive substances.

Conclusions:

• Renin is stored in renal granules as a 43,000 MW form.
• Upon release from granules, renin may convert to a 60,000 MW form by interacting with substances in the soluble fraction of renal-cortical tissue.