Frequently asked questions

Storage, Stability and Documentation

What is the expected shelf life of HuProt arrays? How should they be stored, and how are they shipped?

If HuProt v4.0 arrays are properly stored at -80˚C, the arrays have a shelf life of at least 6 months for most applications. For serum profiling, the arrays are good for at least one year after the date of manufacture.

Are the arrays labile, and how is that measured?

The proteins printed on the arrays are very stable if the arrays are stored at -80˚C. We have performed studies using arrays that are 24 months old and still observed significant binding signals.

Can I obtain SOPs and an MSDS for HuProt arrays?

A user manual and an MSDS are available for HuProt v4.0 arrays. Please visit the Resources page.

Are HuProt arrays CGMP (Current Good Manufacturing Practice) compliant?

HuProt arrays are used primarily as for in vitro research and are not CGMP compliant.

What is the maximum order volume per month? How long is the shipping/delivery time after receiving the order?

Please contact us – we will be happy to discuss your inventory needs with you.

How are the HuProt arrays shipped?

HuProt arrays are placed in plastic slide mailers, which are in turn securely boxed and shipped on dry ice.

I am an overseas client and need a copy of the Commercial Invoice to import the arrays. Can you send us a copy?

If you need a copy of the commercial invoice for customs, please let us know and we will send you a copy in advance.


HuProt Content FAQs

Where can I find the full range of proteins on the HuProt V4.0 array?

For the full list of proteins by name and category please visit HuProt Arrays Resources page.

How are the full-length proteins attached to the glass surface of the arrays?

Standard HuProt arrays are printed on Epoxy slides, and proteins are captured on the surface by epoxysilane groups. Other binding surfaces, including nitrocellulose, are available, depending on your needs. Please contact us to discuss.

Is new content added to the HuProt array regularly?

We add new proteins to the array whenever new full-length cDNA clones are made available.

Are all proteins printed in equal amounts on the HuProt arrays? Are proteins that are normally abundant in the cell normalized to levels similar to the less abundant?

At present, the amount of protein on the array at present is not normalised and varies depending on the protein level expressed in yeast before purification. In some rare cases, the protein levels may be low if the expressed protein is toxic to the yeast cells.

Are membrane proteins represented on the array? If so, is there some detergent present?

The HuProt v4.0 array contains thousands of membrane proteins. The protein printed on the arrays is eluted using a buffer that contains 0.03% TritonX-100.

As the array is spotted with full-length protein (GST tagged), how does that affect the conformation of proteins with transmembrane domains?

We have extensively evaluated the folding of many non-membrane proteins on the HuProt array and will be happy to send you additional information on the folding of non-membrane proteins upon request. We have not performed an in-depth analysis of the folding of membrane proteins. The full protein content on the HuProt arrays can be found on the Resources page

Have the arrays been tested for pH tolerance? For example, I am interested in studying post-translational modifications, which work best at a higher pH > 8.0.

All proteins were eluted in a buffer of pH 8.0 - pH 8.5 and should work well for studies of post-translational modifications.


Serum Profiling FAQs

How much serum should I send to Arrayjet?

Please send 50 μl of frozen serum per sample for analysis, preferably on dry ice. This volume will be sufficient for test dilutions & repeat experiments if needed.

What dilution of serum do you usually use for serum profiling?

We typically use a 1:500 dilution to ensure that the background is low.

What is the minimum amount of sample I can send?

Arrayjet can perform serum profiling using a very small volume of sample (e.g. 15 μl). However, with such small volumes, the HuProt array must be covered with a glass coverslip during incubation. Adding/removing the coverslips can result in scratches or other physical damage to the array surface. If you can afford to send a larger sample of serum (e.g. 50-60 μl), this is highly preferable. We will be able to directly immerse the array in a diluted sample without using a coverslip. As an added precaution, we also incorporate test dilutions using a small number of your samples on test arrays, before conducting the full experiment on all serum samples.


Antibody Cross-Reactivity Testing FAQs

What concentration of mAb is needed for Monoclonal Antibody Cross-reactivity Testing on the HuProt array? How about testing for cross-reactivity?

To test the cross-reactivity of your mAb (“specific hits”), a concentration of 0.1 – 1.0 μg/ml (depending on the affinity) is recommended.

What concentration of mAb do I use to see if it cross-reacts with other proteins on the array other than the antigen?

To test the cross-reactivity of your mAb against other proteins on the array, increase the mAb concentration in your assay to 10 μg/ml.

How many mAb can I test on each array for cross-reactivity? Can the arrays be used more than once? How about competition studies?

Arrayjet recommends that you use each array only once for cross-reactivity testing, as the printed proteins will become denatured when you dry the array before scanning. However, for competition studies, you may add 2 mAbs at the same time to one array (0.1 – 1.0 μg/ml of each mAb).

For antibody cross-reactivity testing, when should I add the anti-GST antibodies for grid alignment, and what wavelength of the scanner should I use to view the anti-GST staining?

When conducting analyses using one mAb sample per array, you can view the anti-GST staining using a wavelength different from that used to stain your mAb. There are two ways to do this:

You may add the anti-GST antibodies and mAb sample to the array at the same time (not recommended).

If you don’t want the anti-GST antibody to compete with your sample mAb or cross-react with your secondary antibody, first conduct the sample mAb assay and scan the array (most protein spots will not be visible). Next, add the anti-GST antibodies to the array, and then apply the grid pattern to your mAb image. Please note that the GST signals will be weak as low concentrations of anti-GST are used. For more information, please contact Arrayjet.