Question

The enzyme secreted by acrosome to dissolve the wall of the ovum.

Answer 1

Hint: The acrosome in a human sperm secretes digestive enzymes. These digestive enzymes function by breaking down the zona pellucida, the outer membrane of the ovum. This allows the haploid nucleus present in the sperm to fuse with the haploid nucleus present in the ovum.

Complete answer: An acrosome is an organ present on the anterior half of the sperm head. It is present in many mammals together with humans. The acrosome is a cap-like structure that is derived from the golgi apparatus of the cell. In higher mammals including humans, the acrosome releases two digestive enzymes, namely, hyaluronidase and acrosin. These two enzymes break down the outer membrane of the ovum, known as the zona pellucida. This facilitates the fusion of the sperm cell with the ovum. Hyaluronidases are the digestive enzymes that catalyze the breakdown of hyaluronic acid in the body. They also increase the permeability of tissue to fluids, hence facilitating the sperm to fuse with the ovum. Acrosin is a trypsin-like protease enzyme that digests the zona pellucida. This enzyme works in the process of the lysis of the zona pellucida. This facilitates the penetration of the sperm through the deepest glycoprotein layers of the ovum.
Additional Information:
The enzymatic mechanism of the enzyme hyaluronidases is the cleavage mechanism. The hyaluronic glucosidases cleave the (1->4)-linkages present between the N-acetylglucosamine and glucuronate. The word hyaluronidase alternatively refers to hyaluronic glucuronidases which cleave the (1->3)-linkages.

Note: Five functional hyaluronidases are present in humans- HYAL1, HYAL2, HYAL3, HYAL4, and HYAL5. These are also called SPAM1 or PH-20. The genes for HYAL1-3 are present on chromosome 3 and the chromosomes for HYAL4-6 are clustered on chromosome 7.