Do the amino acids have to be pre-activated for spotting?
No, the MultiPep RS can activate amino acid derivatives specifically for each cycle. There is a dedicated activation vial for each amino acid. Of course, pre-activated amino acids can also be used.

Are the membranes deprotected in the instrument?
Yes, the MultiPep RS spots piperidine solution on the membrane to take the Fmoc protection group off in each cycle. The membrane can stay in the instrument for the entire synthesis.

How is the membrane washed and dried for the next coupling?
The membrane is clamped tightly in a holder which forms a shallow tray above it. The bottom has tiny holes to remove solvent by vacuum aspiration. Solvent is delivered on the upper face of the membrane and pulled through by vacuum. A longer extraction time is being applied to remove methanol from the final wash and to dry the membrane.

Is the rinsing action sufficient if a full set of peptides is built on the membrane?
Yes, the flow-through mode of washing is very effective and makes economic use of the solvents. Actually it is even more effective than washing manually in plastic trays.

Can we still use Bromophenol blue (BPB) to monitor the reactions?
The MultiPep RS can be programmed to deliver BPB at the appropriate steps in the cycle to stain amino groups on the peptides assembled. The stain is removed with the next coupling reaction as it is done  in manual procedure, too.

Is rinsing only applied on the spot where reagents were delivered?
No, the entire membrane must be washed, even if there is only one single spot to be coupled. In general, the peptides will be of similar length and a significant portion of the membrane is still being spotted.

Is there any possibility of piperidine carryover?
As piperidine is used in a very large excess it must be removed thoroughly. The washing procedure is designed to remove all traces of the reagent before the next coupling will be started.

Can the MultiPep be adjusted to make more than 600 spots on each membrane?
So far, we have worked only with up to 600 spots per membrane which is relatively easy. Very dense arrays may require manual pre-activation (once a day) as the very fine needle tip is not suited for the mixing necessary in the activation procedure.

Is it possible to use a Boc-Lys(Fmoc)-Pro linker and cleave diketopiperazine peptides for QC/QA?
Yes, this can be done and we can supply the respective membrane.

What is the synthesis time for two sets of 600 each 10-mer peptides?
With a recommended double coupling of 2x30 min, 2x5 min deprotection and all washing and drying steps, the total cycle time is about 2.5-3 hours and the two sets of 10mers would be assembled in a little more than a day.

What is the cost of consumables and solvents?
Amino acid derivative sets and membranes are similar to those used in the semi-automated SPOT synthesis on our AutoSpot SL robot. The amount of piperidine used is considerably less (it accounts for most of the overall costs!) and the volume of solvents is also a bit less than in the manual procedure.

Can the synthesis be interrupted and started again?
The MultiPep RS can be stopped and re-started at any time. Several convenient options allow manual procedures (e. g. Bromophenol blue staining or introduction of very unusual derivatives) and safe re-starting in any cycle.