Complex II Home Page

Links to other Complex II sites
What is Respiratory Complex II? Introduction. (pdf) Bioph354 at UIUC(html)

Complex II is a membrane-bound enzyme that oxidizes succinate to fumarate and reduces ubiquinone to ubiquinol. In mitochondria the former reaction is part of the Krebs TCA cycle, while the latter injects electrons into the respiratory chain for energy conservation at a lower level thant NADH.

Protein and NA sequences for chicken Complex II
PDB Structure entries for Complex II and related flavoproteins
SQR structures
QFR structures
Soluble FRD structures (gamma-prbact) (epsilon-prbact) (firmicutes?)
Flavocyt c structures
L-Aspartate Oxidase structures
Tabular comparison of available SQR and QFR structures (pdf).
Which structure has the correct orientation of carboxin?
Crystallization reported in abstract submitted Oct 1998.
Preview of structure of chicken Complex II, June 2005.
Structures with OAA, 3-NP, and carboxin published in JBC 2006
Structures with OAA (hi res), malonate published in BBA 2006
Work on porcine Complex II by ZiHe Rao's group at TsingHua DaXue
Dr. Fei Sun's porcine Complex II at the icsg2006 (gunzipped)
Wolinella succinogenes flavoprotein has a cis-Asp! Model w atom labels is 2BS2, maps calculated with phases from it using SF's sf2bs2.cif. Other model is chicken complex II, superimposing the FAD domain.
Hagerhall's alignment of the small subunits. (Key to species) (from Hagerhall, 1997)

Structural alignment of the small subunits of mitochondrial and E. coli Complex II.

Complex II subunits/sequences

Mitochondrial Complex II Consists of: Four protein subunits, 1116 residues, 123 kDa protein

Prosthetic groups: FAD, Fe2S2, Fe4S4, Fe3S4, Heme B

1. SDHA = Flavoprotein (70 kDa)

Alignment and vertical
more sequences aligned
Bost-SDH-FP
Index aliphatique : 74,38. 1-43 =Transit peptide
Mature chain 622 residues, 68413 kDa, PI 6.37
Question about cutting site, mature start residue, of FP

msgvaavsrl wrarrlaltc tkwsaawqtg trsfhftvdg nkrssakvsd aisaqypvvd
hefdavvvga ggaglraafg lseagfntac vtklfptrsh tvaaqggina algnmeednw
rwhfydtvkg sdwlgdqdai hymteqapas vvelenygmp fsrtedgkiy qrafggqslk
fgkggqahrc ccvadrtghs llhtlygrsl rydtsyfvey faldllmesg ecrgvialci
eervhpphqg qehchrhrsy grtyfsctsa htstgdgtam vtraglpcqd lefvqfhptg
iygagclite gcrgeggili nsqgerfmer yapvakdlas rdvvsrsmtl eiregrgcgp
ekdhvylqlh hlppaqlamr lpgisetami fagvdvtkep ipvlptvhyn mggiptnykg
qvlrhvngqd qgvpglyacg eaacasvhga nrlganslld lvvfgracal siaescrpgd
kvpsikpnag eesvmnldkl rfangsirts elrlnmqksm qshaavfrvg svlqegceki
sslygdlrhl ktfdrgmvwn tdlvetlelq nlmlcalqti ygaearkesr ggprredfke
rvdeydyskp iqgqqkkpfe qhwrkhtlsy vdiktgkvtl eyrpvidrtl netdcatvpp
aigsy

2. SDHB = Iron-sulfur protein (27 kDa)

Sequences.
Alignment, wo bovine
>Homo. Mature form is 29-280, 252 residues,  28,735 kDa:     
        1 maavvalslr rrlpattlgg aclqasrgaq taaataprik kfaiyrwdpd kagdkphmqt
       61 ykvdlnkcgp mvldalikik nevdstltfr rscregicgs camninggnt lactrridtn
      121 lnkvskiypl phmyvikdlv pdlsnfyaqy ksiepylkkk desqegkqqy lqsieerekl
      181 dglyecilca ccstscpsyw wngdkylgpa vlmqayrwmi dsrddfteer laklqdpfsl
      241 yrchtimnct rtcpkglnpg kaiaeikkmm atykekkasv 

>Gallus:
maaavvgvslrrgvparflraglrpvrgleavhgicrgaqtaaaatsrikkfsiyrwdpd
kpgdkprmqtyevdlnkcgpmvldalikikneldstltfrrscregicgscamniaggnt
lactkkidpdlskttkiyplphmyvvkdlvpdlsnfyaqyksiepylkkkdeskqgkeqy
lqsiedrqkldglyecilcaccstscpsywwngdkylgpavlmqayrwmidsrddyteer
laqlqdpfslyrchtimnctrtcpkglnpgkaiaeikkmmatykekaaaa

>Bos (incomplete? aligns w 104-242 of human):
ninggntlactrridtnlskvskiyplphmyvikdlvpdlsnfyaqyksiepylkkkdes
qggkeqylqsiedrekldglyecilcaccstscpsywwngdkylgpavlmqayrwmidsr
ddfteerlaklqdpfslyr

3. SDHC = Anchor protein = cytochrome b L

Alignment,  
Vertical,
Chicken NA alignment w translation
bos cytb (30-169 is mature chain) 140 residues, mw 15,160 Da
        1 maalllrhvg rhclrahlsp qlcirnavpl gttakeemer fwsknttlnr plsphisiyg
       61 wslpmamsic hrgtgialsa gvslfglsal lvpgsfeshl efvkslclgp alihtakfal
      121 vfplmyhtwn girhlmwdlg kgltisqlhq sgvavlvltv lssvglaam

4. SDHD = Anchor protein = cytochrome b S

Alignment
[1-55 is transit peptide]56-159 is 103 residues, 10,997 Da
QPS3bos
        1 malwrlsvlc gakegralfl rtpvvrpalv saflqdrpaq gwcgtqhihl spshhsgska
       61 aslhwtgerv vsvlllglip aaylnpcsam dyslaatltl hshwgigqvv tdyvhgdavq
      121 kaaktgllvl saftfaglcy fnyhdvgick avamlwkl

Keywords: Complex II, Succinate dehydrogenase, SDH, cis-peptid,e x-ray structure, respiratory chain, Kreb's Cycle