msgfPar: Constructor for the msgfPar class

In thomasp85/MSGFplus: An interface between R and MS-GF+

Constructor for the msgfPar class

Description

This function creates an msgfPar object with the specified parameters. If some parameters have not been specified they will not be part of the MS-GF+ call and MS-GF+'s own defaults kicks in; Consult the MS-GF+ documentation for these. Note however that at least a database file is required to run an analysis.

Usage

msgfPar(database, tolerance, isotopeError, tda, fragmentation, instrument,
  enzyme, protocol, ntt, modification, lengthRange, chargeRange, matches)

Arguments

database	The location of the fasta file to use as search database
tolerance	The parent ion tolerance to use. In simple cases a string in the form '20 ppm' or '1 Da' or an msgfParTolerance object if asymmetric tolerance is desired
isotopeError	The range of isotope errors used to correct for non-monoisotopic peaks. Either a numeric vector of length 2 specifying the lower and upper bounds of the range, or an msgfParIsotopeError object
tda	Logical Should Target-Decoy approach be used to calculate FDR values.
fragmentation	An integer specifying which fragmentation has been used during data acquisition. See details.
instrument	An integer specifying the type of instrument used during data acquisition. See details.
enzyme	An integer or name specifying the enzyme that has been used for protein digestion. See details.
protocol	An integer or name specifying the type of preparation that has been done for the samples. See details.
ntt	An integer specifying the cleavage specificity (Number of Tolerable Termini). 2 only allows fully tryptic peptide (if trypsin is used), 1 allows semitryptic peptides and 0 allows unspecific peptides
modification	An msgfParModificationList object or a list containing the named elements nMod and modifications containing respectively an integer with the number of allowed modifications per petide and the modifications to search for as msgfParModification
lengthRange	A two element vector containing the lower and upper bounds of the residue length to search for
chargeRange	A two element vector containing the lower and upper bounds of the charge range to search for
matches	The number of matches to report per spectrum

Details

Please consult the MS-GF+ documentation for full description of the parameters

Fragmentation is usually specified as an integer according to the following lookup

0

As written in the spectrum or CID if no info

1

CID

2

ETD

3

HCD

4

Merge spectra from the same precursor

It is possible to use the full name of the description for a more litteral function call

Instrument can likewise be specified as an integer or as a name according to this list

0

LowRes

1

HighRes

2

TOF

3

QExactive

Enymes are specified in the same manner using the following list

0

Unspecific cleavage

1

Trypsin

2

Chymotrypsin

3

Lys-C

4

Lys-N

5

glutamyl endopeptidase (Glu-C)

6

Arg-C

7

Asp-N

8

alphaLP

9

No cleavage

The protocol informs MS-GF+ whether a special sample treatment has been performed as part of the analysis. The protocol is specified according to the following list

0

No protocol

1

Phosphorylation

2

iTRAQ

3

iTRAQPhospho

Value

An msgfPar object

References

MS-GF+

See Also

Other msgfParClasses: msgfPar-class, msgfParChargeRange-class, msgfParEnzyme-class, msgfParFragmentation-class, msgfParInstrument-class, msgfParIsotopeError-class, msgfParLengthRange-class, msgfParMatches-class, msgfParModification-class, msgfParModificationList-class, msgfParNtt-class, msgfParProtocol-class, msgfParTda-class, msgfParTolerance-class

Examples

# Example of specifying all parameters - usually not necessary
parameters <- msgfPar(
                      database=system.file(package='MSGFplus', 'extdata', 'milk-proteins.fasta'),
                      tolerance='20 ppm',
                      isotopeError=c(0, 2),
                      tda=TRUE,
                      fragmentation='CID',
                      instrument='TOF',
                      enzyme='Lys-C',
                      protocol='No protocol',
                      ntt=2,
                      modification=list(
                          nMod=2,
                          modifications=list(
                              list(name='Carbamidomethyl',
                                   composition='C2H3N1O1',
                                   residues='C',
                                   type='fix',
                                   position='any'
                              ),
                              list(name='Oxidation',
                                   mass=15.994915,
                                   residues='M',
                                   type='opt',
                                   position='any'
                              )
                          )
                      ),
                      lengthRange=c(6,40),
                      chargeRange=c(2,7),
                      matches=1
                     )
parameters

thomasp85/MSGFplus documentation built on Oct. 2, 2024, 9:26 a.m.