TETRAHEDRAL CARBON

3241 Tetrahedral carbon, white. Three equal arms and one socket with axes at 109.5° to each other. Each arm has a square section to locate the keyed protractor . As with all units the connecting arm may join another group or be cut back to represent hydrogen. Thus the unit can also represent the methyl group. It is used for main chain alpha carbons of polypeptides, and the sugar carbons of nucleic acids and polysaccharides.

3252 Tetrahedral carbon, grey. As above for use as side chain carbons for polypeptides.

3261 Tetrahedral carbon, white This is a double socket carbon unit. As above but with one shortened arm containing a narrow socket. In conjunction with the correct digonal O, 4564, this allows ring structures e. g. furanose, polysaccharide, to be formed with a free socket so that they may be joined together.

3270 Tetrahedral carbon, natural. As 3241 but in low density polyethylene, for use when units are to be separated and re-assembled e.g. class practicals.

PEPTIDE BOND (AMIDE)

3281 Peptide bond trans white. This unit represents a planar amide group and has one socket in the carbon atom and an arm on the nitrogen for connection to alpha carbons. Rotation is possible about the N arm and the C socket, but not about the C(O)-N(H) bond.

3290 Peptide bond trans naturalAs 3281 but in low density polyethylene for use with 3270 when units are to be separated and reassembled.

3301 PEPTIDE BOND cis white

3301S As 3301 but with socket in place of N-H arm. Suitable for polyproline I helix.

3313 Peptide bond, amide, blue Planar amide unit with socket in the carbonyl carbon. Use for glutamine and asparagine. The connecting arm on the nitrogen should be cut back to the N-H distance (start of the square section) .

NITROGEN

3323 Tetrahedral nitrogen, blue Three equal arms and one socket are tetrahedrally distributed at 109.5°. In addition to representing tetrahedral nitrogen, this unit also represents a protonated amino group.

4333 Nitrogen planar trigonal, blue Planar amino unit with one connecting arm and a small socket suitable for H-bond of purine and pyrimidine bases.

4343 Nitrogen planar trigonal, blue Planar trigonal nitrogen with 3 connecting arms suitable for substituted amines in purine and pyrimidine bases.

3353 GUANIDINIUM, blue
The planar, protonated guanidinium group for for use in arginine. One standard socket only.

3365 IMIDAZOLE, purple
The imidazole ring with one socket and no connecting arms. Unprotonated.

3375 PHENYL, purple
Planar phenyl ring with one socket and connecting arm in the para position. Use for example in phenylalanine and tyrosine.

3385 INDOLE, purple
Planar Indole ring with one socket in the 3 position. No connecting arms. Use for tryptophan.

3394 PYRROLE, red
Substituted, planar pyrrole ring with 1 socket and 2 connecting arms. A third connecting arm on the methine substituent. Four of these units join together to form the porphyrin skeleton.

4405 PYRIMIDINE RING, purple (used for cytosine)
The unit consists of six atoms in a planar ring with standard sockets at N3, C2 and C6, with a narrow socket at NI to receive an H- bond. The arm at C5 is extended to form a connecting arm for use in 5-halogeno derivatives and hydroxymethycytosine.

4416 PYRIMIDINE RING, olive (used for uracil and thymine)
As 4405, but with a standard socket in NI.

4422 PURINE RING, grey (used for guanine)
The unit consists of 9 atoms moulded in a planar ring with standard sockets at N9, C2 and C6. A narrow socket is provided in the hydrogen arm attached to NI to receive an NI-NI H-bond pin.

4437 PURINE RING, light green (adenine -ring only) This is similar to 4422, but includes an H- arm for the C2 socket. There is a standard socket in NI to receive an NI-NI H-bond pin.

4448 H-BOND PIN Rigid stainless steel pin 0.093" dia. x 1%" overall. A tapered groove at each end assists in gripping the sides of small sockets. It is required for H-bonded base triplets or some of the Hoogsteen base pairs.

445K O-NH2 H-BOND This unit consists of the H-bond pin 4448 with red keto oxygen unit 4514 and the blue amino unit 4333 moulded on either end to give the correct H-bond distance when used for base pairs. The keto and amino units can rotate about the pin, which can be forcibly removed and reassembled.

446K N1-N1 H-BOND This unit is only required for A T and AU base pairs, which are best ordered as such. There is an olive green H-arm at one end and a light green insert at the other end of the H- bond pin 4448. It gives the correct inter- base H-bond distance.

3474 VINYL/ETHYLENE Planar unit with one socket and 3 arms.

3488 METAL ATOM Expanded polystyrene sphere, includes pins for attachment.

3494 CARBOXYL lonised. One socket in the carbon atom.

KETO OXYGEN, red

4514 One connecting arm and small socket for H-bond e.g. keto oxygen in purine: pyrimidine base pairs.

4525 As 4514 but without small socket.

5504 One socket in carbon arm and one connecting arm.

4534 OXYGEN, red lonised. Sphere with socket.

DIGONAL OXYGEN, red

4544 One socket and one connecting arm at an angle of 110°. Suitable for linking carbons. (See below for ring structures) .

4554 One socket and one connecting arm at an angle of 119°. For use with phosphorus atom and nucleic acids.

4564 One socket and one short narrow dia- meter connecting arm for use in ring struc- ture e.g. furanose and pyranose rings, in con- junction with double socket carbon. (This allows ring structures to be formed with a free socket for attachment to other units).

3574 HYDROXYL, red One socket in the oxygen atom.

3589 SULPHYDRYL and DIGONAL SULPHUR, yellow One socket in the sulphur atom. Shorten arm to give sulphydryl. Disulphide bonds are formed by linking with yellow plastic sleeving included with cystine, kits, or if requested.

4594 PHOSPHORUS This is an irregular tetrahedron, to the latest DNA and RNA values of Arnott et al. The main chain bonds are 1.60 A. The unit has one socket to receive digonal 0 normally attached to sugar C5 (04) and a square sec- tion arm to set torsional angle to the oxygen (01) attached to C3' of the next sugar.

421K. G C: Purine ring in grey

4422 and C ring in purple 4405, are supplied joined with H-bond pin and with 2 O-NH2 units 445K, which only need to be inserted.

422K A U: Purine ring and H-arm in light green 4437 and pyrimidine ring in olive 4416, N1-N1 H-bond 446K and one O-NH2 unit 445K.

423K A T: As 422K A U but with methyl group 3252.

MAGNETIC UNITS

These demonstrate the complementarity of the base pairs by using magnets in place of the stainless steel H-bonds. The magnets should be arranged so that the donor atom has the North pole exposed and the acceptor the South pole. Consequently, the donor-acceptor relationship of the base pairs is simulated exactly and it is impossible, for example, to pair A with C.

4620 MAGNETS

Magnets are supplied in high grade Alcomax 111, they are .093" in diameter x .625".

413K CODON KIT

The codon kit consists of units for magnetic mRNA pentanucleotide (UUG + 2 others) and magnets to convert tRNA PHE anticodon, together with 1 phenylalanine residue to demonstrate codon:anticodon relationship.

414K NAD KIT

A pyrimidine ring is used for the pyridine ring.

415K NADP KIT

465K DEOXYRIBOFURANOSE PHOSPHATE RING KIT

This consists of 4 white tetrahedral carbons, 3241, 1 white double socket carbon, 3261, 1 narrow arm ring oxygen, 4564, 2 long arm oxygens, 4554, 2 ionised oxygens, 4534, and 1 phosphorus unit, 4594.

466K RIBOFURANOSE PHOSPHATE RING KIT

Same as 465K but with the addition of 1 hydroxyl, 4574.

4590 T PIECES 1/8" x 1/8"

These are used to join a horizontal rod to a vertical rod, and are moulded in nylon in two halves. Clamping is effected by tightening the single stainless steel screw.

4600 T PIECES 5/32" x 1/8"

The first dimension is the top of the T. Otherwise as for 4590.

4610 ANODISED ALUMINIUM ROD

This is available in two feet lengths at 5/32" and 1/8" diameter. It is polished and anodised to natural finish.

BASEBOARDS (Approximate dimensions)

360B 20"x14"x3/4" (50cmx35cmx2cm)
361B 22"x18"x3/4" (55cmx45cmx2cm)
362B 26" x 22" x 3/4" (66 cm x 55 cm x 2 cm)
363B 31"x19"x3/4" (79cmx48cmx2cm)

These baseboards are made from transparent perspex and are supplied with polished edges. They have the advantage over wooden baseboards that the baseboard plan can be placed under the board and removed and replaced at will. Please refer to price list to see size of baseboard required for each protein.

364B Afromosia baseboard 4" x 9" x '1/2"

4620 WATSON UNIVERSAL CLAMP

The clamp consists of a saddle and collar. The collar or bush is 318 inch diameter drilled for 118 inch rod, and tapped for 2 x 6BA screws for gripping the rod and saddle respectively. The saddle passes round the unit and is gripped by the clamping screw on the collar. The second collar set screw grips the rod. Collars, screws and saddles may be supplied separately. These clamps form a universal mounting enabling the unit to be placed in any desired orientation about a supporting rod. As such they can be used as an alternative to drilling the peptide bond unit.