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	HBS Design
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written by Kevin Drew (Bonneau Lab), kdrew@nyu.edu

General Description:
This demo shows how to run the hbs_design application.  A hydrogen bond surrogate (HBS) is a helical mimetic scaffold used for inhibiting protein interactions. The demo shows the design of an hbs inhibitor for the MDM2-P53 protein interaction.

Algorithm:
1. Pertubation phase: rigid body movement of hbs wrt target
2. Design phase: design user specified residues on hbs scaffold and minimize
3. Repeat 10x

Command:
hbs_design<.exe> -database <path to your database> @input/flags

Input files:
./input/flags = user specified options
./input/mdm2_hbs.pdb = input structure where target is chain 1 and hbs is chain 2

Options:
-hbs_design_positions = residues on hbs to design (numbering is relative to hbs, for example 3 is the third residue on hbs), default repacks with no design
-pert_num = number of pertubations during pertubation phase, default 10, production 100
-design_loop_num = number of pertubation + design cycles, default 10, production 10
-nstruct = production 1000

Pre Processing:

Post Processing:
Similar to other multi chain design protocols, the ddG is computed and is a good indicator of a good design.  First sort by total score, take top 5 percent and then sort by REPACK_ENERGY_DIFF (ddG).

Limitations: 
This app is inflexible to adjusting monte carlo temperatures, score functions, degree of rigid body pertubations, designing noncanonical amino acids, etc. The app also requires the hbs is close to a plausible binding mode with respect to the target.