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Ch.16 Amino Acids, Proteins, and Enzymes
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
All textbooksTimberlake 13th EditionCh.16 Amino Acids, Proteins, and EnzymesProblem 58b
Chapter 16, Problem 58b

Fresh pineapple contains the enzyme bromelain that hydrolyzes peptide bonds in proteins.
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b. Fresh pineapple is used in a marinade to tenderize tough meat. Why?

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Fresh pineapple contains the enzyme bromelain, which is a proteolytic enzyme. Proteolytic enzymes are specialized in breaking down proteins by hydrolyzing peptide bonds.
Meat is primarily composed of muscle proteins, which contribute to its toughness. These proteins are held together by peptide bonds.
When fresh pineapple is used in a marinade, the bromelain enzyme interacts with the proteins in the meat, catalyzing the hydrolysis of peptide bonds. This breaks the proteins into smaller peptides and amino acids.
The breakdown of proteins reduces the structural integrity of the muscle fibers, making the meat softer and more tender.
This enzymatic action is why fresh pineapple is effective in tenderizing tough meat when used in a marinade.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Bromelain

Bromelain is a proteolytic enzyme found in fresh pineapple that breaks down protein molecules by hydrolyzing peptide bonds. This enzymatic activity is responsible for the tenderizing effect of pineapple on meat, as it helps to denature and degrade the proteins, making the meat softer and easier to chew.

Protein Hydrolysis

Protein hydrolysis is a biochemical process where peptide bonds in proteins are broken down into smaller peptides or amino acids, often facilitated by enzymes like bromelain. This process is crucial in cooking and food preparation, as it alters the texture and digestibility of proteins, enhancing the overall quality of the dish.
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Acidic Hydrolysis Concept 1

Marinade

A marinade is a mixture typically composed of acidic ingredients, oils, and seasonings used to soak food, particularly meat, before cooking. The acid in marinades, such as those from fruits like pineapple, helps to tenderize the meat by promoting protein hydrolysis, while also infusing flavor into the dish.
Related Practice
Textbook Question

Adults who are lactose intolerant cannot break down the disaccharide in milk products. To help digest dairy food, a product known as Lactaid can be added to milk and the milk then refrigerated for 24 hours.

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a. What enzyme is present in Lactaid, and what is the major class of this enzyme?

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Textbook Question

Adults who are lactose intolerant cannot break down the disaccharide in milk products. To help digest dairy food, a product known as Lactaid can be added to milk and the milk then refrigerated for 24 hours.

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b. What might happen to the enzyme if the Lactaid were stored at 55 °C?

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Textbook Question

Fresh pineapple contains the enzyme bromelain that hydrolyzes peptide bonds in proteins.

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a. The directions for a gelatin (protein) dessert say not to add fresh pineapple. However, canned pineapple where pineapple is heated to high temperatures can be added. Why?

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Textbook Question

Identify the amino acids and type of interaction that occurs between the following R groups in tertiary protein structures:

a.

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Textbook Question

Identify the amino acids and type of interaction that occurs between the following R groups in tertiary protein structures:

c. —CH2—SH and HS—CH2—

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Textbook Question

What type of interaction would you expect between the following in a tertiary structure?

a. threonine and glutamine

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