add more types

src/types.jl

@@ -5,3 +5,28 @@
 Type of optional values.
 """
 const Maybe{X} = Union{Nothing,X}
+
+"""
+$(TYPEDEF)
+
+Information about isozyme composition including subunit stoichiometry and
+turnover numbers.
+
+# Fields
+$(TYPEDFIELDS)
+"""
+Base.@kwdef mutable struct Isozyme
+    gene_product_stoichiometry::Dict{String,Float64}
+    kcat_forward::Maybe{Float64} = nothing
+    kcat_backward::Maybe{Float64} = nothing
+end
+
+"""
+$(TYPEDSIGNATURES)
+
+A convenience constructor for [`Isozyme`](@ref) that takes a string gene
+reaction rule and converts it into the appropriate format. Assumes the
+`gene_product_stoichiometry` for each subunit is 1.
+"""
+Isozyme(gids::Vector{String}; kwargs...) =
+    Isozyme(; gene_product_stoichiometry = Dict(gid => 1.0 for gid in gids), kwargs...)