Nukleinsavak - Szerves Kémiai Tanszék

A nukleinsavak monomerjeiDNSRNS

A pentofuranoid gyűrűk téralkata a nukleinsavakbanA-DNS, RNSB-DNS

A nukleinsavak primer szerkezete

Oligo(poli)nukleotidkonformációNucleic acidequivalent of theRamachandranplot illustrating thetheoreticallyallowed angles ofζ and α.Illustration of oligo-polydeoxynucleotide chain sectionhighlighting the two atomic segments C4 C3 O3 P (lightblue) and P O5 C5 C4 (red). Each segment acts as arigid, coplanar unit, hence behaves as a virtual bondpivoting at phosphate. Key dihedral angles involved thatcharacterise conformation are ζ, the angle subtendedabout the O3 P bond and α, the angle subtended aboutthe P O5 bond. The same arguments apply in oligopolynucleotidechains too.

Oligo(poli)nukleotidkonformációConformationalfreedom is heavilyrestricted in nucleicacids owing to lack offree rotation aboutO3-P and P-O5 bonds.Free rotation isprimarily dampedowing to the gaucheeffect in which lonepair-σ* orbitaloverlaps inphosphodiester links togenerate double bondcharacter in O-Pbonds that restrict freerotation.OOs* P-O n O3'3'O OO O5'5'OP PO OOO Os* P-On Oa nemkötõ elektronpár helyzetea síkban van a sík elé mutat a sík mögé mutat

Oligo(poli)nukleotid konformációIllustration of conformational preferences of the conformational angle γ subtendedabout the C4 C5 bond. Each deoxynucleotide (or nucleotide) residue adoptseither a +sc or ap conformation. The former is usually preferred but forexceptional circumstances.

A DNS szerkezeteX-ray diffraction pattern ofDNA. The spots forming a crossin the center denote a helicalstructure. The heavy bands at theleft and right arise from therecurring bases.

A DNS Watson-Crick-modelljének (B-forma) adatai

Bázispárok a DNS-ben (Watson-Crick modell)

A DNS szerkezet változataiA-formaB-forma (balra)A-forma (középen)Z-forma (jobbra)B-formaZ-forma

A DNS szerkezet változataiB-forma A-forma Z-formaSzínkód: foszfodiészter lánc és a furanózgyűrűk – zöld; purin bázisok – piros;pirimidin bázisok – kék.

A DNS szerkezetek adatai

DNS szuperszerkezetekSchematic illustration of closed circular DNA in open conformation (left)and then in a negative supercoiled conformation (middle) and positivesupercoiled conformation (right).

RNS típusok jellemzői

Nukleinsavak szekvenálásaThe basic strategy of nucleic acid sequencing is identical to that for otherbiomacromolecules, namely:• the specific and reproducible cleavage of the biopolymer chain into fragmentsand fractionation of the fragments of manageable size to be fully sequenced;• the sequencing of the individual fragments;• the repetition of the preceding steps using a degradation procedure that yields aset of the fragments that overlap the cleavage sites in the previous set(s);• the ordering of the fully sequenced fragments using the information from theoverlapped cleavage sites via different degradation procedures.Elválasztás: nagyfelbontású poliakrilamid gélelektroforézis (high-resolutionpolyacrylamide gel electrophoresis - hrPAGE)Maxam-Gilbert-módszer: Kémiai hasításSanger-módszer: Enzimes lánclezárás/didezoxi módszerRNS - tömegspektrometria

Nukleinsavak kémiai szintézise

Purinok előállításabElektrofil centrumNukleofil centrum

Nukleozidok előállítása – Fischer–Helferich-módszer

Nukleozidok előállítása – Vorbrüggen-módszer

Nukleotidok előállítása – Yoshikawa-módszer

Nukleinsavak szintézise

Nukleinsavakszintézise -kulcsreakciók

Nukleinsavak szintézise - capping

Pirimidinek és pirimidin nukleozid analógok gyógyászati felhasználásaPirimidin(barbitursav)származékok- szedatívumokIdoxuridine is used in the treatment of Herpes infections of the eyeAZT is the most widely used anti-AIDS drug3-TC (Lamivudine) is used to treat both hepatitis B and AIDSd4T (Stavudine) is approved for treatment of HIV infection and AIDS.

Purinszármazékok és gyógyászati felhasználásuk6-Mercaptopurine is used in the treatment of leukemia and other cancers.Acyclovir is an antiviral agent used in the treatment of Herpes infections.DDI is used in the treatment of AIDS.Caffeine (1,3,7-trimethylxanthine) is the well known stimulant present in tea andcoffee.In mammals the end product of metabolic breakdown of nucleic acids is urea, butin birds and reptiles it is uric acid.Sildenafil – Viagra®

A nukleinsavakbiológiai szerepeThe central dogma of molecularbiology deals with the detailedresidue-by-residue transfer ofsequential information. It statesthat such information cannot betransferred from protein to eitherprotein or nucleic acid.F. Crick,Nature, 227 (1970) 561-563.General Special UnknownDNA → DNA RNA → DNA protein → DNADNA → RNA RNA → RNA protein → RNARNA → protein DNA → protein protein → protein

A fehérjeszintézisvázlataProtein synthesis overviewhttp://images.google.hu/imgres?imgurl=http://www.frontiers-ingenetics.org/en/pictures/ribosome_1.jpg&imgrefurl=http://www.frontiers-ingenetics.org/page.php%3Fid%3Dproteinsynthesis_en&usg=__M6RssLL9sr8KKSUBVSHgDmcawQM=&h=318&w=300&sz=39&hl=hu&start=36&um=1&itbs=1&tbnid=eUMx3R0Eo933RM:&tbnh=118&tbnw=111&prev=/images%3Fq%3Dribosome%26start%3D20%26um%3D1%26hl%3Dhu%26newwindow%3D1%26sa%3DN%26rlz%3D1T4RNWE_enHU310HU310%26ndsp%3D20%26tbs%3Disch:1

A transzkripcióSchematic of Transcription Bubble. The complementary strand of DNA in theregion of a gene acts as a template upon which to synthesize mRNA with theassistance of Watson-Crick base pairing. Watson-Crick base pairing ensures thatthe mRNA nucleoside sequence is the RNA equivalent of the deoxynucleosidesequence found in the sense strand of DNA. Hence coding information in sensestrand DNA is smoothly transcribed into an mRNA form for translation intopolypeptide sequences.

A genetikai kód

A transzlációTranslation-moviehttp://images.google.hu/imgres?imgurl=http://bioweb.uwlax.edu/GenWeb/Molecular/Theory/Translation/ribosome.jpg&imgrefurl=http://bioweb.uwlax.edu/GenWeb/Molecular/Theory/Translation/translation.htm&usg=__Fnjr8iUxWTPs43uWlVYwQ23RjjA=&h=406&w=574&sz=35&hl=hu&start=40&um=1&itbs=1&tbnid=oBOf9p--h60m9M:&tbnh=95&tbnw=134&prev=/images%3Fq%3Dribosome%26start%3D20%26um%3D1%26hl%3Dhu%26newwindow%3D1%26sa%3DN%26rlz%3D1T4RNWE_enHU310HU310%26ndsp%3D20%26tbs%3Disch:1

A nukleinsavak kutatásának története1869. Meischer isolated nucleic acids, which he called nuclein.1880. Fischer identified pyrimidines and purines.1884. Hertwig suggested the role of nuclein in heredity.1910. Kossel was awarded the Noble prize for demonstrating the presence of twopyrimidines (cytosine and thymine) and two purines (adenine and guanine) in nucleicacids.1924. Feulgen, developing the fuchsin staining technique, showed that chromosomescontain DNA.1938. Behrens showed that most of the DNA is in the nucleus, and most of the RNA in thecytoplasm.1938. Astbury and Bell showed that the bases in a DNA molecule are stacked one abovethe other, and lie with their planes perpendicular to the long axis of the molecule.1944. Avery, MacLeod and McCarty presented first evidence that DNA is the geneticmaterial.1947. Chargaff showed that DNA contains equal proportions of purines and pyrimidines.1950. Wilkins and coworkers showed that the purine and pyrimidine bases are placedregularly along the DNA molecule at a distance of 3.4A. The molecules are twisted into ahelix with one complete turn every 34A.1952. Hershey and Chase showed that in the T2 virus DNA is the sole carrier of geneticinformation form parent to offspring.1953. Watson and Crick suggested the double helix modell.1960-ies. Deciphering the genetic code.2001-2003. Human genom sequence.

Ismert genom szekvenciákBacteria Haemophilus influenzae and Escherichia coliYeasts Saccharomyces cerevisiae and Schizosaccharomyces pombeNematode Caenorhabditis elegansFruit fly Drosophila melanogasterPlant Arabidopsis thalianaMouse Mus musculusHuman Homo sapiens

Nukleotidok egyéb funkciói