Q.24 A protein without its prosthetic group is known as
(A) apoprotein
(B) hemoprotein
(C) holoprotein
(D) lipoprotein
Apoprotein vs Holoprotein: Understanding Proteins Without Prosthetic Groups
A protein stripped of its prosthetic group is called an apoprotein, making option (A) the correct answer in this biochemistry multiple-choice question. This distinction is key in studying conjugated proteins like enzymes and hemoglobin. Mastering these terms helps in exams and research on protein function.
Correct Answer
The right choice is (A) apoprotein. An apoprotein refers to the protein portion alone after removal of its non-protein prosthetic group, such as heme in hemoglobin or a cofactor in enzymes. This leaves the core polypeptide chain without the tightly bound component needed for full activity.
Option Breakdowns
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(A) Apoprotein: Defines the protein devoid of its prosthetic group, common in contexts like apoenzymes (enzymes minus cofactors).
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(B) Hemoprotein: Describes a conjugated protein specifically with heme as the prosthetic group, like myoglobin or cytochromes, not the protein alone.
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(C) Holoprotein: Represents the complete, functional protein with its prosthetic group attached, fully active unlike the apoprotein.
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(D) Lipoprotein: Refers to a complex of protein and lipid, unrelated to prosthetic groups in enzymes or metalloproteins.
Prosthetic Group Role
Prosthetic groups are non-amino acid molecules permanently bound to proteins, enabling catalysis or oxygen transport. Without them, proteins lose specificity and function, as seen in biochemistry texts. This apo/holo framework applies across molecular biology.
