Drug Discovery
beyond kinetic measurements, thus mitigating the cost to own with increased versatility. Looking back to label based-methods, the Motulsky Mahan method has been useful histori- cally utilising competition between cold and radio- labelled compounds (although it would be equally applicable to fluorescence labels) to directly meas- ure on and off-rates of compounds. This method has been especially applied to GPCR receptors. With Biacore-like methods, the protein of interest must be immobilised on the sensor chip and this has thus far proved difficult with GPCR receptors (previously achieved only for the more accessible case of the oestrogen receptor, strides are being made in screening of membrane bound GPCRs using SPR17 but this still remains a challenging area). This methodology, although laborious, finds favour in some laboratories due to familiarity with the techniques employed and no requirement for additional specialist knowledge or equipment. Throughputs achieved can be substantial, limited only by the stamina of the scientist. A majority of laboratories using this methodology will rely upon radiochemical labelling due to the difficulties in achieving fluorescence labelling that does not induce steric hindrance to the interaction being measured. Custom production of radiolabelled lig-
Table 5: Key features of various kinetic measurement technologies TECHNOLOGY
VENDOR CAPITAL COSTS
ands can be conducted by a number of specialist providers. Where an iodinated product is pre- ferred, the relatively short half life limits users to local suppliers, hence in Europe PerkinElmer (cov- ering the range of materials previously supplied by NEN) and Quotient Bioresearch Ltd (which has acquired the Amersham business from GE) would likely be first choice. Where a tritiated compound would be satisfactory, US-based suppliers such as RC TriTec, ViTrax, Tjaden and Moravek could be considered.
As a final comparator, a newer label-free tech- nique, localised SPR (LSPR), can be considered alongside these more established methods. LSPR shares the advantages of the label-based methods and the ForteBio Octet in being microtitre plate based – a big advantage for a laboratory conduct- ing a range of assay types, but unlike ForteBio and all other biosensor instruments, requires no spe- cialised equipment (measurement is via a standard absorbance reader). To date LSPR has been used to measure affinities, but since the method can follow the association of compound with protein it should, in principle, be possible to derive the off- rate from the measured affinity and on-rate. While there is no evidence yet of proof of principle, such an approach would be very attractive particularly
CONSUMABLE COSTS PER
DATA POINT**
Surface Plasmon Resonance
Biacore, SensiQ, Fujifilm Pharma and others
Localised Surface Plasmon Resonance
Pharma- diagnostics
$0.5-1 Million (varies with extent of autom’n)
Nil*1
$1.5-$3 (mainly the cost of the sensor)
Flow cell based
FORMAT
THROUGHPUT DATA
POINTS/DAY
Theoretical maximum 4,800 In practice, less than 200 per day
$0.2-$0.75 (throughput dependent)
Microtitre plate based
Specialist skill for data interpretation and for sensor regeneration
Any competent screening scientist
Kinetic data possible in theory – practical proof currently absent
Biolayer interferometry
ForteBio $400-600K $1.5-$3
Microtitre plate based
Specialist skills for data interpretation
SKILLS BASE REQUIRED
OTHER
Radiochemical (Motulsky Mahan method)
Configure in house
Nil*2
Medium
Microtitre plate based
>5,000
Any competent screening scientist
Time
consuming and laborious. Radioactivity usage
*assumes that the laboratory has access to general laboratory equipment. 1 absorbance reader, 2 scintillation counter. ** author’s estimates 44 Drug Discovery World Summer 2011
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92