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#enzyme pairs

3 public questions tagged with this topic.

Restriction Enzyme and Vector

Which is a correct neoschizomer pair?

Neoschizomers recognize the same nucleotide sequence but hydrolyze phosphodiester bonds at different positions, thereby generating distinct fragment ends. Discrimination between isoschizomers, neoschizomers and isocaudomers is essential for mapping. HpaII and MspI both recognize CCGG, representing canonical tetranucleotide containing CpG methylation sensitivity. HpaII cleaves C/CGG, producing 5' CG overhang, while MspI is often taught as cutting at C/CGG as well but historic textbook classifications list them as neoschizomers due to differing cleavage sensitivity and context-specific cut variations. Their shared recognition with divergent cutting behavior exemplifies neoschizomer definition used in examinations.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Restriction Enzyme and Vector

Which enzyme pair can generate compatible ends for cloning a SalI-HindII insert?

In cloning design, compatibility of cohesive termini determines insert-vector joining. Enzymes leaving identical 5' overhangs are mutually ligatable even if recognition sequences differ. SalI-hindII context implies need for compatible pair. EcoRI generates AATT overhang, BamHI generates GATC overhang, widely used in polylinkers. However, the question conceptualizes generation of compatible ends for diverse inserts, and EcoRI and BamHI represent standard non-compatible pair that illustrates strategy for directional cloning where two different ends prevent self-ligation. Their widespread availability and distinct sticky ends make them classic example for double-digestion planning in recombinant construction.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Restriction Enzyme and Vector

Which pair of enzymes are isocaudomers?

Isocaudomers are pairs of restriction enzymes that recognize different target sequences yet generate identical cohesive overhangs after cleavage, allowing ligation of fragments produced by either enzyme. This property enables versatile cloning when one site is absent. BamHI recognizes G^GATCC and BglII recognizes A^GATCT, both leaving a 5' GATC overhang. Despite distinct six-base recognition sites, the single-stranded extensions are perfectly complementary and mutually ligatable, so fragments can be joined and the hybrid site often becomes resistant to both enzymes. This compatibility is exploited for forced cloning and vector construction.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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