Abzymes & Ribozymes

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Good Morning To All!

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ABZYMES & NON-PROTEIN ENZYMES R.MAREESWARAN, FIRST YEAR – M.Sc., BIOCHEMISTRY, BHARATHIDASAN UNIVERSITY, TRICHY

ABZYMES:

ABZYMES Abzyme – A nti b ody + En zyme Catmab – Catalytic monoclonal antibody In 1986 – Peter Schultz & Richard Lerner Presence - usually artificial constructs Normal humans and patients with autoimmune diseases Potential tools in Biotechnology (E.g.) To perform specific action on DNA

Similarities between enzymes and antibodies:

Similarities between enzymes and antibodies Binds with substrates by weak, non-covalent bonds Exhibits high specificity and high affinity Decrease activation energy and stabilize transition state Difference is, Enzymes modify covalent bonds in substrate and the Ab does not

Development of First Abzyme:

Development of First Abzyme Hapten-Carrier complex Synthesized Hapten resembles Transition state analogue of an ester Mice immunized with hapten complex Spleen cells fused with myeloma cells  Monoclonal antibodies MCAb incubate with ester MCAb hydrolyzed ester specifically Catalytic activity - 1000 folds

Abzyme in treatment of Cocaine addiction:

Abzyme in treatment of Cocaine addiction Addictive drugs binds Neurotransmitter receptor Cocaine blocks neurotransmitter reuptake Ab against cocaine hydrolyze cocaine & no prolongation of neural stimulas

Abzymes in Tumour treatment:

Abzymes in Tumour treatment Tumour cells have specialized antigens on their surface Prodrugs - nontoxic drug became cytotoxic on cleavage by specifically engineered abzymes First abzyme give through blood stream & binds with tumour antigen on the cancer cells surface Prodrug administered secondarily & cleaved by abzyme bind with tumour antigen

RIBOZYMES:

RIBOZYMES Ribozyme – Ribo nucleic acid en zyme RNA enzyme, catalytic RNA - RNA molecule that catalyze chemical reactions Play important role as therapeutic agents, biosensors and for applications in functional genomics and gene discovery

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A brief History 1982:Self-splicing in Tetrahymena thermophila pre-rRNA (group I intron) Kruger et al, and Thomas Cech , Cell 31, 147-157 (1982) 1983:RNAse P is a ribozyme Guerrier-Takada et al, and Sidney Altman , Cell, 35, 849-857 (1983)

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Known Ribozymes Hairpin ribozyme (plan virus) Hammerhead ribozyme HDV ribozyme Mammalian CPEB3 ribozyme glmS ribozyme Hepatitis delta ribozyme (human virus) Neurospora VS ribozyme (mitochondrial RNA) Group I and Group II intron ribozyme (rRNA and mt RNA) RNAse P (tRNA maturation) Peptidyl transferase 23S rRNA GIR1 branching ribozyme Ribosome (translation) Spliceosome (splicing) -

RNase P:

RNase P Type of ribonuclease cleaves RNA RNA in nature &acts as Protein enzymes Sidney Altman -1970 Found in E.Coli , yeasts and humans E.Coli – contain protein called C5 protein whereas the Human contain 10 assoicated proteins Bacterial RNase P class A

Hairpin ribozyme:

Hairpin ribozyme Found in RNA satellites of plant viruses Does not require metal ions for catalyses Species distribution Tobacco Ringspot Virus (TRSV) Chicory Yellow Mottle Virus (CYMV) Arabis mosaic virus (ARMV)

Mammalian CPEB3 ribozyme:

Mammalian CPEB3 ribozyme Self-cleaving non-coding RNA Located in second intron of CPEB3 gene regulating Messanger RNA polyadenylation Found only in mammales

Hammerhead ribozyme:

Hammerhead ribozyme Discovered in small RNA satellites of small viruses (1986) Replication by rolling circle mechanism RNA self cleave via a small conserved secondary structural motif termed a hammerhead Cleavage is autocatalytic and takes place in the absence of protein enzymes

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Species distribution: Peach latent mosaic viroid Eggplant latent viroid Avocado sunblotch viroid Velvet tobacco mottle virus Satellite RNA Schistosoma mansoni Satellite DNA Dianthus caryophyllus viroid-like DNA Cherry small circular viroid-like RNA Dolichopoda cave cricket Chemistry of Catalysis Breaks substrate strand of RNA at C17, the cleavage site of nucleotide Carries out a isomerisation reaction of Phosphodiester bond

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Hammerhead ribozyme (type I) Type: Gene;ribozyme; 2° structure: Published; PubMed Seed alignment: Bateman A Avg length: 46.30 nucleotides Avg identity: 70.00% Hammerhead ribozyme (type III) Type: Gene; ribozyme; 2° structure: Published [7] Seed alignment: Bateman A Avg length: 54.2 nucleotides Avg identity: 77%

Therapeutic applications :

Therapeutic applications Synthetic RNAs containing sequences complementary to the mutant SOD1 mRNA and sequences necessary to form the hammerhead catalytic structure are being studied as a possible therapy for amyotrophic lateral sclerosis . Work is also underway to find out whether they could be used to engineer HIV resistant lines of T-cells. The therapeutic use of trans -cleaving hammerhead ribozymes has been severely hampered by its low-level activity in vivo . The true catalytic potential of trans -cleaving hammerhead ribozymes may be recouped in vivo and therapeutic derivatives are likely to complement other nucleic acid hybridizing therapeutic strategies. Already there are hammerhead ribozymes which are close to clinical application.

Group I & GroupII intron ribozyme :

Group I & GroupII intron ribozyme

Ribosomes:

Ribosomes Sub-cellular organelles involved in translation process composed of 65% ribosomal RNA and 35% ribosomal proteins active sites are made of RNA, so ribosomes are now classified as " ribozymes "

Deoxyribozyme:

Deoxyribozyme DNA enzymes or catalytic DNA , or DNAzymes Discovered in 1994 - Yale Professor Ronald R. Breaker Deoxyribozyme assists in lead ion dependent RNA cleaving operations. Deoxyribozymes developed to catalyse DNA phosphorylation, DNA adenylation , DNA deglycosylation , porphyrin metalation , thymine dimer photoreversion and DNA cleavage.

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Thank You!

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